GIFT  OF 
Daughter  of  William 

Stuart  Smith»U.S.Navv 


ENGINEERING  !  12 


LOSS  BY  RADIATION  OF  ENTIRE  PRODUCER  BIO  B.T.U. 


GAS, GASOLINE  AND  OIL 
ENGINES 


INCLUDING 


COMPLETE  GAS  ENGINE 
GLOSSARY 


A   Simple,   Practical   and   Comprehensive   Book   on   the 

Construction,  Operation  and  Repair  of  All  Kinds 

of  Engines.    Dealing  with  the  Various  Parts 

in  Detail   and  the  Various  Types  of 

Engines    and   Also    the   Use   of 

Different  Kinds  of  Fuel. 


By 

JOHN  B.  RATHBUN, 

// 

Consulting    Gas     Engineer,    Editor     "Ignition,"     formerly    Instructor     Chicago 
Technical     College,    Author    Gas     Engine    Troubles     and    Installation. 


1919 


CHICAGO  ' 


PUBLISHERS 


5 


(COPYRIGHTED    1918 
BY 

STANTON  &  VAN  VLIET  CO. 


DMH^ 

ENGINEERING  LIBRARY 


TABLE  OF  CONTENTS 


CHAPTER  I.  Heat  and  Power.  Heat  Energy,  Mechanical 
Equivalent  of  Heat,  Expansion  Heat  Units,  Heat  En- 
gines, Efficiency,  External  and  Internal  Combustion 
Engines,  Compression,  Working  Medium 5 

CHAPTER  II.  Working  Cycles.  Definitions  of  Cycle, 
Four  Stroke  Cycle,  Two  Stroke  Cycle,  Two  Port 
Two  Stroke,  Three  Port  Three  Stroke,  Reversing, 
Scavenging,  Junker  Two  Stroke  Cycle 26 

CHAPTER  III.  Fuels.  Calorific  Values  of  Fuels,  Solid, 
Liquid  and  Gaseous  Fuels,  Kerosene,  Gasoline,  Crude 
Oil,  Producer  Gas,  Illuminating  Gas,  Coal,  Benzol...  41 

CHAPTER  IV.  Indicator  Diagrams.  Practical  Use  of  the 
Indicator,  Pressure  Measurement,  Reading  the  Card, 
Four  Stroke  Cycle  Card,  Defects  in  Practical  Working, 
Two  Stroke  Cycle  Card,  Diesel  Card,  Effects  of  Mix- 
ture, Effects  of  Ignition 72 

CHAPTER  V.  Typical  Four  Stroke  Cycle  Engines.  Single 
Cylinder,  Four  Cylinder  Automobile,  Opposed  Type, 
V  Type,  Tandem,  Twin  Tandem,  Rotary  Cylinder, 
Radial  Diesel,  Knight,  Argyle,  Rotary  Valve 87 

CHAPTER  VI.    Typical  Two  Stroke  Cycle  Engines.    Two 

Port,  Three  Port,  Marine,  Controlled  Port,  Aeronautic, 
Oechehauser,   Gnome   Rotary  Two  Stroke,  Koerting. . .    144 

CHAPTER  VII.  Oil  Engines.  Elyria,  Marine.  Diesel  In- 
stallation, Aspiration  Types,  Fairbanks  Morse,  Kero- 
sene Carburetion,  Diesel,  Semi  Diesel,  Combustion  of 
Heavy  Oils 160 

CHAPTER  VIII.  Ignition  Systems.  Hot  Tube  System, 
Low  Tension  System,  High  Tension  System,  Details 
of  Make  and  Break,  Batteries,  Low  Tension  Magnetos, 
High  Tension  Magnetos,  Coils,  Adjustment,  Troubles..  195 

CHAPTER  IX.  Carburetors.  Principles  of  Carburetion, 
Jet  Carburetors,  Water  Jacketing,  Fuel  Supply,  Differ- 
ent Types  of  Auto  Carburetors,  Adjustment  of  Car- 
buretor Troubles  .  271 


86G775 


TABLE  OF  CONTENTS 

CHAPTER  X.    Lubrication.    Forced  Feed,  Splash  System, 

Oil  Pumps,  Lubrication  Troubles 285 

CHAPTER  XI.     Cooling  Systems.     Evaporation  Systems, 

Radiators,  Air  Cooling 299 

CHAPTER  XII.  Speed  Governors.  Automatic  Station- 
ary, Adjustment,  Mixture,  Control,  Hit  and  Miss,  Mixed 
Systems  308 

CHAPTER   XIII.     Glossary.     Definitions   of   Gas   Engine 

Words  and  Phrases 324 


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'GAS,  GASOLINE  AND  OIL        j 
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CHAPTER  I   • 
PRINCIPLES  OF  THE  HEAT  ENGINE 


HEAT  ENGINES.  Heat  energy  and  mechanical  energy  are 
mutually  convertible;  that  is,  heat  energy  can  be  converted 
into  mechanical  energy,  and  mechanical  energy  can  be  con- 
verted into  heat  energy.  The  production  of  heat  through  fric- 
tion is  a  very  common  example  of  the  latter  form  of  conversion, 
while  the  transformation  of  heat  into  mechanical  energy  is 
represented"  by  the  steam  and  gas  engines.  Since  these  engines 
transform  heat  into  mechanical  force  and  motion  they  are 
known  as  "Heat  Engines,"  to  distinguish  them  from  other 
forms  of  prime  movers  in  which  electricity  or  the  kinetic 
energy  of  falling  water  is  utilized  as  a  source  of  energy.  In 
both  the  gas  engine  and  steam  engine,  the  transformation  is 
accomplished  by  the  expansion  of  a  heated  gas  or  vapor,  the 
temperature  of  the  gas  falling  as  the  expansion  proceeds,  the 
energy  liberated  being  proportional  to  the  reduction  in  tem- 
perature. 

In  practical  heat  engines,  the  heat  energy  is  supplied  to  the 
gas  or  water  vapor  by  a  process  known  as  "Combustion"  a 
chemical  combination  of  the  atmospheric  oxygen  with  sub- 
stances known  as  "Fuels."  The  fuels  are  carbon  and  hydrogen 
compounds  such  as  coal,  petroleum,  or  wood,  and  each  sub- 
stance is  capable  of  developing  a  certain  definite  amount  of 
heat  for  every  pound  of  weight.  The  fuel  can  therefore  be  con- 
sidered as  a  heat  storage  system  since  the  original  heat  energy 
imparted  to  the  fuel  by  the  sun  during  the  period  of  plant 
growth  can  later  be  liberated  by  the  process  of  combustion. 
Nearly  all  fuels  are  the  result  of  plant  growth,  the  structure 
being  modified  by  various  conditions  of  pressure,  aging,  and 
atmospheric  conditions  imposed  after  the  death  of  the  plant. 

5 


6  HEAT  ENGINES 

During  combustion,  the  oxygen  of  the  air  combines  with 
the  carbon  and  hydrogen  of  the  fuel  to  form  other  gases, 
commonly  known  as  "Products  of  Combustion."  These 
gases  are  entirely  different  in  character  from  the  original  ele- 
ments of  the  fuel  as  they  must  always  contain  a  percentage 
of  chemically  combined  oxygen.  For  this  reason,  every  fuel 
requires  a  definite  amount  of  oxygen  to  burn  it  to  its  lowest 
form.  The  heat,  of  combustion  is  then  applied  to  the  gas  used 
kt  'jtie  expansio-n  -(working  medium). 

MECHANICAL  EQUIVALENT  OF  HEAT.  The  unit 
of  heat  quantity  used  in  this  country  is  the  British  Thermal 
Unit.  Numerically  this  is  the  amount  of  heat  required  to  raise 
one  pound  of  water  through  a  temperature  of  one  degree 
Fahrenheit.  Thus,  if  one  pound  of  water  is  raised  from  40°  to  60* 
F,  the  temperature  increase  will  be  20°,  hence  this  will  require 
the  addition  of  20  British  Thermal  Units  (B.  T.  U.).  If  100 
pounds  of  water  is  used  instead  of  one  pound,  the  heat  quantity 
will  be  increased  100  times,  or  100  X  20  =  2,000  B.  Y.  U.'s.  If  any 
other  working'  medium  than  water  is  considered  the  results  above 
must  be  multiplied  by  the  "Specific  Heat"  of  the  substance.  Thus 
if  the  specific  heat  of  oxygen  is  0.156,  the  number  of  B.  T.  U.'s 
required  to  raise  100  pounds  through  20°  Fahrenheit  will  be 
given  by:  20  X  100  X  0.156  =  312.0  B.  T.  U.'s. 

It  has  been  found  by  experiment  that  778  foot-pounds  of 
mechanical  energy  will  produce  1  B.  T.  U.,  and  conversely, 
1  B.  T.  U.  =  78  foot-pounds.  The  heat  contained  in  the  water 
of  the  above  example  will  produce  2,000  X  778  =  1,556,000 
foot-pounds  of  mechanical  energy.  If  this  heat  is  liberated  in  one 
minute,  then  1,556,000 -i- 33,000  =  47.15  horsepower,  the  figure 
33,000  being  the  number  of  foot-pounds  per  minute  required 
for  1  horsepower.  In  actual  practice  we  can  hardly  expect  to 
utilize  more  than  30  percent  of  this  power  owing  to  the  many 
losses  that  take  place  in  a  heat  engine.  From  this  problem 
it  will  be  seen  that  we  can  determine  the  power  of  a  heat  engine 
if  we  know  the  heat  supplied  and  the  percentage  of  losses  in 
the  engine. 

ELEMENTS  OF  THE  HEAT  ENGINE.  When  heat  is 
applied  to  a  gas  contained  within  a  closed  vessel,  the  pressure 
will  rise  with  every  increase  in  temperature,  providing  that  the 
volume  of  the  vessel  is  kept  constant.  If  this  vessel  is  pro- 
vided with  a  means  of  increasing  or  expanding  the  volume  of 


HEAT  ENGINES 


Section  Through  Four  Stroke  Cycle  Aeronautic  Motor,  Showing  Cylinder 
and  Valves. 


8  HEAT  ENGINES 

the  contents,  the  pressure  will  fall  during  the  expansion  if  no 
more  heat  is  supplied  during  this  time.  In  the  first  case,  where 
heat  is  supplied  to  the  gas,  energy  is  being  given  to  the  work- 
ing medium.  During  the  expansion,  the  heat  content  is  re- 
duced and  work  is  being  given  up  in  giving  motion  to  the  ex- 
panding walls  of  the  vessel.  The  production  of  mechanical 
energy  by  the  heat  engine  therefore  requires  an  alternate  in- 
crease and  decrease  in  the  temperature  of  the  gas. 

The  most  common  method  of  obtaining  mechanical  effort  from 
an  expanding  gas  is  to  enclose  it  in  a  hollow  cylinder,  provided 
with  a  freely  sliding  piston  as  shown  by  Fig.  1.  The  movement 
of  the  piston  provides  a  means  of  varying  the  volume  and 
therefore  permits  the  expansion  of  the  enclosed  working  me- 
dium. Cylinder  (c)  is  provided  with  the  sliding  piston  (P), 
the  latter  being  shown  in  two  positions  by  the  solid  and  dotted 
lines,  the  outer  position  being  at  (M)  and  the  inner  at  (N).  At 
the  left  end  of  the 'cylinder,  the  bore  is  closed  by  the  wall  or 
cylinder  head  (R).  The  heating  chamber  (B)  is  connected  with 
the  contents  of  the  cylinder  by  the  hollow  tube  (O),  and  the 
chamber  (B)  is  heated  by  the  lamp  (L).  In  moving  from  the 
position  (M)  to  (N),  the  piston  turns  the  shaft  (S)  through 
the  crank  (X)  and  the  connecting  rod  (T). 

Consider  the  bulb  (B),  and  the  space  between  the  cylinder 
head  and  the  piston  at  (M),  to  be  filled  with  some  gas  such  as 
air,  this  being  at  a  comparatively  low  temperature.  The  lamp 
(L)  is  now  placed  under  the  bulb  (B),  and  the  temperature  of 
the  enclosed  air  is  greatly  increased.  This  results  in  an  increase 
in  pressure  and  the  piston  moves  to  the  right,  or  from  (M) 
to  (N),  thus  performing  mechanical  work  on  the  driving 
shaft  (S).  If  the  lamp  is  removed  at  the  instant  that  the  piston 
starts  to  move,  the  increasing  volume  will  cause  a  reduction 
in  the  pressure  and  temperature.  After  the  piston  has  reached 
the  outer  end  of  the  stroke  at  (N),  the  temperature  must  be 
reduced  to  the  original  temperature,  or  the  pressure  must  be  re- 
leased before  the  piston  returns  to  its  original  position.  When 
returned  to  (M),  more  gas  is  heated,  and  the  piston  performs 
a  second  working  stroke,  and  so  on,  a  continuous  production  of 
mechanical  effort  being  produced  by  an  alternate  heating  and 
cooling  of  the  working  medium.  An  increased  amount  of  work 
can  be  obtained  by  applying  heat  continuously  through  the 
working  stroke  and  thus  maintaining  a  higher  working  pressure. 
In  practice,  the  charge  is  not  cooled  at  the  end  of  the  stroke, 
but  is  allowed  to  escape  to  the  atmosphere  under  pressure, 


HEAT  ENGINES  9, 

but  the  final  result  is  the  same  in  either  case  as  far  as  heat 
economy  is  concerned. 

In  Fig.  2  the  heating  of  the  working  medium  is  obtained 
in  another  way.  The  medium  in  this  case  consists  of  a  mix- 
ture of  air  and  some  combustible  gas,  such  as  coal  gas  or 
gasoline  vapor.  With  the  piston  at  (H),  and  the  space  J-H 


L. 


Fig.    1    Shows    Heat    Applied    Externally    to    Cylinder    C    by    the    Lamp 

Fig.    2    Shows    the    Combustion    of    the    FueJ    Taking    Place    within    the 
Cylinder. 


filled  with  the  inflammable  mixture,  a  spark  is  applied  to  the 
gas  and  combustion  occurs  directly  within  the  cylinder  bore. 
This  increases  the  temperature  tremendously,  and  the  pressure 
due  to  the  combustion  drives  the  piston  (P)  to  the  right,  turn- 
ing the  crank  (G).  As  no  more  heat  is  applied  after  the  piston 
leaves  (H),  the  gas  expands  and  decreases  in  pressure  during 
the  stroke.  At  the  point  (I),  the  pressure  is  reduced  by  open- 
ing a  valve  to  atmosphere,  thus  allowing  the  piston  to  be  re- 
turned to  (H)  for  the  next  power  impulse. 


10  HEAT  ENGINES 

TYPES  OF  HEAT  ENGINES.  According  to  the  method 
adopted  in  supplying  heat  to  the  cylinder,  heat  engines  may  be  di- 
vided into  two  principal  classes:  (1)  External  combustion  engines 
in  which  the  combustion  occurs  outside  of  the  cylinder  walls  as 
in  Fig.  1,  and  (2)  Internal  combustion  engines  in  which  the  com- 
bustion is  completed  within  the  cylinder  as  in  Fig.  2.  The  steam 
engine  is  an  example  of  the  external  combustion  engine  while 
the  gas  engine  is  an  internal  combustion  type.  Both  types  have 
been  used  with  great  success,  but  the  adoption  of  either  of  the 
engines  depends  upon  the  conditions  of  the  service.  Each  en- 
gine has  its  particular  fields  of  usefulness 

With  the  internal  combustion  engine,  a  greater  percentage 
of  the  heat  is  applied  usefully  to  the  piston,  the  only  losses 
being  those  due  to  radiation  and  the  exhaust.  The  fuel  must 
be  supplied  in  gaseous  form.  The  many  heat  losses  of  the  ex- 
ternal combustion  type  are  to  some  extent  compromised  by  the 
possibility  of  burning  cheap,  readily  accessible  fuels,  and  in 
some  cases  the  external  combustion  engine  is  actually  cheaper 
to  run  than  the  internal  combustion  type  owing  to  local  fuel 
and  labor  conditions. 

THE  STEAM  ENGINE.  Fig.  3  shows  the  layout  of  an  ele- 
mentary steam  plant.  Heat  is  supplied  by  the  burning  fuel  (C), 
under  the  boiler  (B),  the  heat  being  transmitted  to  the  water 
(W)  by  contact  with  the  flames,  and  by  the  heat  passing1 
through  the  tubes  (X).  The  steam  from  the  boiler  passes  to 
the  engines  cylinder  (E)  through  the  steam  main  (R).  The 
products  of  combustion  caused  by  the  burning  of  the  fuel  escape 
from  the  firebox  through  the  smoke  stack  (S),  and  these  gases 
carry  a  considerable  amount  of  heat  with  them.  Heat  is  also 
lost  by  radiation  from  the  boiler  and  piping. 

The  piston  (P)  slides  freely  in  the  bore  of  the  cylinder  (E), 
and  is  connected  with  the  shaft  through  the  piston  rod  (H), 
the  connecting  rod  (G),  and  the  crank  (F).  The  belt  J-J 
transmits  power  from  the  fly-wheel  (I)  to  the  machinery  that  is 
to  be  driven.  Steam  from  the  boiler  enters  the  valve  chest 
(A)  by  the  pipe  (R),  and  from  this  point  the  steam  is  alternately 
admitted  and  exhausted  from  the  cylinder  ends  (L)  and  (K) 
by  the  valve  (V).  This  engine  is  of  the  double  acting  type,  that 
is,  steam  is  alternately  admited  on  either  side  of  the  piston  (P) 
so  that  pressure  is  applied  twice  per  revolution.  The  arrange- 
ment is  such,  that  while  steam  is  being  admitted  to  one  end,  it 
is  allowed  to  escape  from  the  other  end  through  the  exhaust 


HEAT  ENGINES 


11 


pipe  (N).     The  valve  is  operated  from  the  crankshaft  through 
the  valve  rod  (H). 

A  detail  of  the  valve  action  is  shown  by  Fig  3a  in  which  the 
piston  (P)  is  moving  to  the  right  as  indicated  by  the  arrow. 
The  live  boiler  steam  enters  the  cylinder  through  the  port 
(g)  as  shown  by  the  arrows,  and  the  exhaust  escapes 
through  the  port  (h),  the  exhaust  cavity  (M),  and  the  exhaust 


Fig.    3.      Steam    Engine    Operation. 

pipe  (Z).  Fig  3b  shows  the  valve  position  when  the  piston  is 
moving  in  the  opposite  direction,  the  exhaust  now  being  through 
the  port  (g),  and  the  live  steam  admission  through  port  (h). 
The  valve  shown  is  the  simple  "D"  type,  but  on  the  modern 
engine  this  is  considerably  modified  and  elaborated  upon. 

The  speed  is  held  constant  at  different  loads  by  varying 
the  period  of  steam  admission  to  the  cylinder,  the  valve  re- 
maining open  for  a  shorter  part  of  the  stroke  with  a  light  load 
than  when  the  engine  is  heavily  loaded.  A  modern  engine  gen- 


12 


HEAT  ENGINES 


erally  cuts  off  the  steam  at  about  one-quarter  of  the  stroke 
when  running  at  the  rated  power,  and  at  about  one-half  stroke 
when  fully  overloaded.  From  the  point  of  cut-off  the  steam 
expands  to  the  end  of  the  stroke,  and  by  this  expansion  the 
quantity  of  steam  used  per  horsepower  is  much  reduced  below 
the  consumption  that  would  result  from  allowing  the  steam  to 
follow  the  piston  throughout  the  length  of  the  stroke — even 
with  a  smaller  cylinder.  The  valve  travel  is  regulated  by  a  cen- 
trifugal or  inertia  type  governor. 


Fig.  4.  Diagrammatic  View  of  Elementary  Gas  Engine  Using  Liquid  FueJ. 
Vapor  is  Formed  at  J,  Enters  Cylinder  H  Through  the  Inlet  Valve  B, 
and  is  Ignited  by  Spark  Plug  C.  Explosion  Drives  Back  Piston  P,  the 
Burnt  Gas  Then  Being  Exhausted  Through  Exhaust  Valve  A  and  Pipe  M. 


THE  GAS  ENGINE.  The  most  common  form  of  gas  engine 
or  internal  combustion  engine  is  shown  by  Fig  4.  The  cylinder 
barrel  (H)  contains  the  single  acting  piston  (P),  the  latter  being 
connected  with  the  crank  (F)  by  the  connecting  rod  (G). 
While  gas  engines  of  large  size  are  made  with  double  acting 
pistons,  by  far  the  greater  majority  are  single  acting  with 
the  pressure  applied  at  one  end  as  shown.  The  cylinder  is  sur- 
rounded with  the  water  jacket  (W)  which  prevents  overheating 
by  the  successive  combustions.  The  combustible  gas  mixture  is 


HEAT  ENGINES  13 

admitted  to  the  cylinder  through  the  admission  or  inlet  valve 
(B),  while  the  burnt  or  exhaust  gases  are  allowed  to  escape 
through  the  exhaust  valve  (A),  and  the  exhaust  pipe  (M).  When 
gaseous  fuels  such  as  illuminating  or  producer  gas  are  used 
they  are  mixed  with  the  proper  amount  of  air  in  a  mixer  con- 
nected to  the  inlet  valve,  so  that  when  the  latter  opens,  the  suc- 
tion of  the  piston  fills  the  cylinder  with  a  combustible  mixture 
through  the  inlet  valve.  When  liquid  fuels  such  as  gasoline  or 
kerosene  are  used,  the  liquid  is  sprayed  in  with  the  proper 
amount  of  air.  The  heat  vaporizes  the-^pray  and  forms  a  highly 
combustible  gaseous  mixture.  The  spraying  and  proportioning 
of  the  liquid  fuel  is  performed  by  a  device  known  as  a  car- 
bureter, and  is  shown  in  its  simplest  form  by  (J).  The  fuel- 
nozzle  (J)  extends  into  the  inlet  pipe,  and  during  the  suction 
stroke,  sprays  the  liquid  fuel  into  the  entering  air  at  the  end 
of  the  pipe.  The  spray  consisting  of  very  finely  subdivided 
particles  is  vaporized  by  a  slight  addition  of  heat,  and  forms  a 
combustible  mixture.  The  spray  nozzle  (J)  is  connected  to  the 
fuel  tank  (T). 

With  the  inlet  valve  (B)  open,  and  the  piston  moving  to 
the  right  on  the  suction  stroke,  the  cylinder  is  filled  with 
the  mixture.  The  inlet  valve  closes  near  the  end  of  the  suc- 
tion stroke,  and  on  the  return  stroke  the  mixture  is  com- 
pressed to  a  comparatively  high  pressure.  At  the  end  of  the 
compression  stroke  at  the  left,  a  spark  occurs  at  the  spark 
plug  (C),  which  ignites  the  compressed  mixture,  and  starts 
the  combustion.  The  increased  pressure  due  to  the  combustion 
drives  the  piston  toward  the  right  on  the  "power"  or  "working 
stroke,"  and  near  the  end  of  this  stroke  the  exhaust  valve  (A) 
opens  and  relieves  the  pressure.  This  sequence  is  followed  in 
the  "four  stroke  cycle"  type  of  gas  engine. 

A  preliminary  compression  of  the  mixture  is  necessary  to 
increase  the  final  working  pressure.  Within  certain  limits,  the 
higher  the  compression  the  higher  will  be  the  explosion  pres- 
sure. A  great  deal  depends  upon  the  proportion  of  the  mixture 
and  its  uniformity.  There  should  be  just  enough  air  to  com- 
plete the  combustion  of  the  gas  or  oil  vapor.  If  the  air  and 
vapor  are  not  thoroughly  mixed,  the  combustion  will  not  be 
complete,  and  hence  some  of  the  fuel  will  be  expelled  through 
the  exhaust.  A  particle  of  air  must  be  in  contact  with  every 
particle  of  fuel  for  complete  and  instantaneous  combustion. 
The  spark  should  occur  at  the  point  of  highest  compression, 
or  rather  the  combustion  should  be  completed  before  the  piston 


14  HEAT  ENGINES 

has  moved  far  on  the  working  stroke.  If  the  combustion  is 
slow,  much  heat  will  be  wasted  to  the  walls  and  through  the 
exhaust.  Under  proper  conditions  the  temperature  of  com- 
bustion in  a  gas  engine  cylinder  is  very  high,  probably  being 
between  2,500  and  3,000  degrees  Fahrenheit. 

COMPARISON  BETWEEN  INTERNAL  AND  EXTER- 
NAL COMBUSTION  ENGINES.  The  efficiency,  or  fuel  econ- 
omy, of  any  heat  engine  depends  upon  the  range  of  tem- 
peratures during  the  period  of  expansion.  If  the  steam  or 
burning  gas  at  the  beginning  of  the  working  stroke  has  a 
very  high  temperature  and  is  then  expanded  to  a  very  low 
temperature  at  the  end  of  the  stroke  the  efficiency  will  be  much 
higher  than  with  a  low  initial  or  high  exhaust  temperature. 
If  the  gas  is  not  expanded  down  to  a  low  temperature,  much 
heat  will  be  lost  when  the  exhaust  valve  is  opened  to  the  atmos- 
phere. The  theoretical  efficiency  is  the  relation  of  the  heat 
reduction  in  the  cylinder  to  the  total  heat  supplied.  Thus,  if  the 
working  medium  (gas)  is  heated  to  3,000  degrees  at  the  be- 
ginning of  the  working  stroke,  and  is  reduced  to  500  degrees  at 
the  end  of  the  stroke,  just  before  the  exhaust  opens,  the  tem- 
perature range  in  the  cylinder  will  be  3,000  —  500  =  2,500  degrees. 
The  efficiency  will  be  the  ratio  of  the  temperature  range  to  the 
initial  temperature,  or  2,500-1-3,000  =  0.833  (83.3  percent).  As- 
suming that  the  initial  temperature  is  only  1,500  degrees,  but 
with  the  exhaust  temperature  still  at  500  degrees,  then  the 
theoretical  efficiency  will  be:  1,500  —  500-4-1,500  =  0.666  or  66.6 
percent.  This  does  not  take  the  mechanical  efficiency  of  the 
working  parts  into  account,  and  hence  is  often  known  as  the 
"Thermal  efficiency." 

With  steam  engines  the  initial  temperature  is  practically 
limited  to  about  500°  Fahrenheit  since  a  higher  temperature 
would  result  in  almost  unmanageable  steam  pressures.  The 
pressure  of  steam  increases  much  more  rapidly  with  a  given 
temperature  than  with  air  or  any  fixed  gas,  hence  the  initial 
temperature  in  internal  combustion  engines  may  be  much  higher 
than  that  employed  with  steam  engines.  If  saturated  steam  is 
raised  to  500°  the  corresponding  pressure  will  be  about  700 
pounds  per  square  inch,  a  pressure  that  is  almost  impossible 
to  handle  satisfactorily  under  practical  working  conditions. 
With  air  as  the  working  medium,  a  temperature  of  3,000°  does 
not  cause  prohibitive  stresses  in  the  material, 


HEAT  ENGINES 


15 


16  HEAT  ENGINES 

There  are  many  other  losses  in  the  steam  plant,  such  as 
radiation  and  friction  losses  in  the  steam  pipes,  radiation  from 
the  boiler  settings  and  engine  surfaces,  heat  loss  up  the  stack, 
power  required  for  auxiliaries  such  as  feed  pumps,  cylinder  con- 
densation, etc.  While  the  temperature  in  the  boiler  furnace 
approximates  2,000°,  the  temperature  of  the  steam  at  the  cylinder 
is  only  in  the  neighborhood  of  350°,  or  16  percent  of  the  furnace 
temperature.  By  generating  the  saturated  steam  at  a  com- 
paratively low  pressure  and  temperature,  and  then  "superheating 
it  after  its  generation,  the  economy  of  the  steam  engine  has  been 
considerably  increased.  Unfortunately  the  temperature  of  the 
superheat  is  limited  and  is  much  lower  than  in  the  gas  engine. 
The  superheat  reaches  this  limit  at  about  550  to  600  degrees. 
The  efficiency  of  a  modern  steam  plant  equipped  with  super- 
heaters is  only  about  20  percent,  while  an  internal  com- 
bustion engine  of  the  Diesel  type  may  exceed  40  percent. 

SUPERHEATING  AND  CONDENSING.  Fig.  5  shows  a 
diagram  of  the  method  adopted  in  increasing  the  temperature 
range  of  a  steam  plant  by  means  of  the  superheater  and  con- 
denser. The  superheater  increases  the  temperature  of  the  steam 
supply  while  the  condenser  reduces  the  temperature  of  the 
steam  rejected.  In  practice,  either  method  is  often  used  inde- 
pendently. 

Saturated  steam  is  generated  at  the  required  pressure  in 
the  boiler  (K),  the  hot  gases  of  combustion  passing  up  through 
the  flues  (L),  and  out  at  the  stack.  A  pipe  coil,  or  equivalent, 
called  the  "Superheater,"  (M)  is  placed  in  the  smoke  box  (B) 
where  it  is  subjected  to  the  heat  of  the  waste  gas.  One  end  of 
the  superheater  coil  is  connected  with  the  boiler  at  (J),  the 
other  end  of  the  coil  being  connected  with  the  steam  engine 
cylinder  (N)  by  the  pipe  (A)  so  that  the  boiler  steam  passes 
through  the  superheater  coil  on  its  way  to  the  engine  cylinder. 
Heat  is  thus  supplied  to  the  steam  without  burning  extra  fuel 
since  the  heat  added  is  that  which  would  otherwise  pass  up 
the  stack.  This  increase  in  temperature  does  not  increase  the 
pressure  but  simply  increases  the  heat  contents. 

The  exhaust  from  the  engine  passes  to  the  condenser  coil 
(E)  through  the  pipe  (D),  the  condenser  coil  being  contained  in 
a  condenser  tank  (F)  filled  with  cold  water.  On  striking  the 
cold  walls  of  the  tubes  the  heat  of  the  exhaust  steam  is  ab- 
sorbed, and  the  steam  is  condensed,  thus  creating  a  partial  vacu- 
um in  the  condenser  coil  and  the  exhaust  pipe  (D).  Instead  of 


HEAT  ENGINES 


17 


18  HEAT  ENGINES 

exhausting  against  the  atmosphere  the  engine  now  exhausts 
against  a  much  lower  pressure  which  in  effect  is  equivalent 
to  increasing  the  steam  pressure.  Thus,  if  the  atmospheric  pres- 
sure is  taken  at  14.7  pounds  per  square  inch,  and  the  pressure 
in  the  condenser  as  5.0  pounds,  it  is  equivalent  to  adding 
14.7  —  5.0  =  9.7  pounds  per  square  inch  to  the  boiler  pressure. 
When  exhausting  to  atmosphere,  the  steam  temperature  is 
above  212  degrees,  but  as  the  exhaust  temperature  depends 
upon  its  pressure,  it  is  evident  that  the  condensed  steam  rejected 
from  the  condenser  is  much  below  212  since  the  condenser 
pressure  is  below  the  atmospheric.  This  increases  the  tem- 
perature range  by  lowering  the  temperature  of  rejection. 

An  "Air  pump"  (G)  is  connected  to  the  lower  end  of  the 
condenser  coil  which  pumps  out  the  water  of  condensation  as 
at  (O).  Cold  water  circulation  in  the  condenser  is  maintained 
by  the  circulating  pump  (H)  and  this  is  rejected  at  (I).  Both 
the  water  (O),  and  the  rejection  water  (I)  flow  into  the  "Hot 
well"  (S).  From  the  hot-well,  the  warm  water  is  drawn  through 
the  pipe  (P)  by  the  pump  (Q),  and  is  fed  into  the  boiler  through 
the  pipe  (R)  to  make  up  for  the  water  lost  by  evaporation. 
Some  of  the  heat  contained  in  the  rejection  water  from  the 
condenser  is  thus  returned  to  the  boiler  and  is  saved,  but  as  the 
water  required  for  condensation  is  many  times  the  quantity 
used  by  the  boiler,  a  greater  part  of  the  heat  from  the  con- 
denser is  wasted.  Some  steam  is  also  wasted  in  driving  the 
condenser  pumps  (G)  and  (H),  so  that  condensing  is  not  a 
clear  gain. 

A  plant  exhausting  directly  into  the  atmosphere,  without 
a  condenser  is  known  as  a  "Non-condensing  plant."  As  the 
steam  escapes  at  a  higher  temperature  the  exhaust  losses  are 
higher,  but  this  is  to  some  extent  overcome  by  the  fact  that 
the  exhaust  steam  can  be  used  to  heat  the  feed  water  to  a  higher 
temperature  than  can  be  attained  with  the  condenser.  The 
feed  water  heater,  like  the  condenser  generally  consists  of 
a  coil  of  pipe  surrounded  by  a  shell,  the  pipe  being  filled  with 
the  boiler  feed  water  while  the  outer  space  surrounding  the  pipe 
is  filled  with  exhaust  steam  from  the  engine.  The  water  is  heated 
to  from  200  to  210  degrees.  The  heater  not  only  affords  fuel  econ- 
omy but  also  reduces  the  stresses  and  strain  on  the  boiler  shell 
that  would  result  from  the  injection  of  cold  water  into  the  hot 
boiler.  Owing  to  the  low  temperature  of  the  water  taken  from 
the  hot  well  of  condensing  plants  (110  to  130  degrees)  an  addi- 
tional feed  water  heater  is  used  which  uses  the  exhaust  steam 


HEAT  ENGINES 


19 


20  HEAT  ENGINES 

from  the  feed,  air,  and  circulating  pumps  for  raising  the  tem- 
perature of  the  hot  well  water. 

MULTIPLE  EXPANSION  ENGINES.  When  the  steam 
is  expanded  in  a  series  of  cylinders  instead  of  the  single  cylinder 
illustrated,  there  is  a  smaller  heat  loss  by  condensation  within 
the  cylinders.  An  engine  in  which  the  expansion  is  carried 
out  in  more  than  one  cylinder  is  known  as  a  "Multiple  ex- 
pansion engine"  and  may  be  compound,  triple  expansion,  or 
quadruple  expansion  according  to  whether  the  expansion  is 
carried  out  in  two,  three,  or  four  stages.  In  a  compound  engine, 
the  boiler  steam  is  first  admitted  to  the  small  "High-pressure 
cylinder,"  and  when  a  part  of  the  expansion  is  performed, 
exhaust  enters  the  larger  low  pressure  cylinder  in  which  it  is 
further  expanded. 

The  low  pressure  cylinder  must  be  considerably  greater 
in  volume  than  the  high  pressure  in  order  to  accommodate  the 
increased  volume  of  steam  due  to  the  first  expansion. 

In  a  triple  expansion  engine,  the  partially  expanded  steam 
from  the  high  pressure  cylinder  passes  into  a  large  cylinder 
known  as  the  "Intermediate."  After  a  second  expansion  in  the 
intermediate,  the  steam  is  discharged  for  the  final  expansion 
in  the  low  pressure  cylinder.  This  is  a  very  complicated  engine 
and  is  only  suitable  for  very  large  engines  used  in  marine 
service  or  in  water  works. 

Compound  gas  engines  have  been  repeatedly  proposed  by 
people  not  familiar  with  gas  engine  conditions,  believing  that  the 
same  saving  would  result  from  successive  expansions  of  the 
gas,  as  in  the  case  of  the  steam.  The  very  reverse  is  true, 
since  in  the  use  of  two  cylinders,  more  heat  is  absorbed  by  the 
more  greatly  extended  cooling  surface  of  the  cylinder  walls.  The 
cylinder  walls  of  a  steam  engine  are  insulated  so  that  there  is 
little  heat  loss  by  radiation,  and  hence  the  multiple  cylinder 
idea  is  perfectly  practicable.  In  the  case  of  the  gas  engine,  all 
of  the  cylinder  wall  surface  must  necessarily  be  cooled,  hence 
any  increase  in  wall  surface  due  to  the  addition  of  cylinders 
leads  to  an  additional  heat  loss  to  the  jacket  water. 

STEAM  TURBINES.  Since  power  is  the  result  of  a  force 
in  motion,  we  can  obtain  the  same  results  with  a  great  pres- 
sure and  small  velocity  as  in  the  case  of  the  steam  turbine 
piston,  or  we  can  expand  the  steam  to  a  high  velocity  and 
utilize  the  energy  of  impact  on  the  running  wheel  blades  of 


HEAT  ENGINES 


21 


a  steam  turbine.  In  both  cases  the  benefits  of  expansion  are 
realized,  but  according  to  different  methods.  With  the  steam 
turbine,  steam  under  pressure  is  allowed  to  issue  from  a  nozzle 
into  a  lower  pressure,  with  the  result  that  the  steam  expands  in 
proportion  to  the  pressure  on  the  discharge  side  of  the  nozzle, 
and  the  velocity  of  the  stream  is  enormously  increased.  The 
potential  energy  is  thus  partly  or  entirely  converted  into  kinetic 
energy.  The  stream  of  steam  on  striking  a  surface  such  as  the 


Partial  Section  Through  Four  Cylinder  Automobile  Engine  Showing 
Cooling  Radiator  R. 

"Paddle"  or  blade  of  a  turbine  wheel  creates  a  driving  force  and 
turns   the   turbine   wheel. 

Essentially,  a  steam  turbine  consists  of  a  series  of  stationary 
nozzles  and  a  series  of  small  blades  mounted  on  the  periphery 
of  a  running  wheel.  The  velocity  of  the  wheels  is  very  high  to 
compensate  for  the  low  pressure  of  impact,  and  for  the  most 
efficient  results  the  blade  velocity  should  be  about  two-thirds  of 
the  jet  velocity.  This  cannot  be  attained  in  practice  owing 
to  the  limiting  whirling  strength  of  our  materials,  hence  the  ex- 


22  HEAT  ENGINES 

pansion  is  carried  out  in  a  number  of  wheels,  so  that  the  nozzle 
velocity  at  any  one  stage  of  expansion  is  comparatively  low. 
By  restricting  the  expansion  at  each  set  of  nozzles  the  velocity 
can  be  kept  so  low  that  the  running  wheel  velocity  can  be  made 
to  more  nearly  meet  the  ideal  speed  relation.  In  water  turbines, 
the  velocity  of  the  water  is  so  low  that  it  is  an  easy  matter  to 
get  the  correct  relation  between  the  velocity  of  the  water  and 
the  running  wheel  in  one  stage,  or  with  a  single  wheel.  Like 
the  water  turbine,  the  steam  machine  can  be  divided  into  two 
principal  classes;  the  impulse  and  reaction  types.  All  turbines, 
.however,  work  on  the  same  elementary  principles;  that  is, 
motion  and  power  are  obtained  by  the  impact  of  a  fluid  stream 
on  a  series  of  blades  attached  to  one  or  more  running  wheels. 

During  the  past  few  years  there  has  been  considerable  ex- 
perimental work  done  with  gas  turbines  but  as  yet  nothing 
of  a  practical  nature  has  been  developed.  The  high  temperatures 
attained  by  the  burning  gas,  and  the  necessity  of  compressing 
the  combustible  mixture  have  been  some  of  the  greatest 
obstacles  to  the  success  of  the  gas  turbine.  In  one  turbine,  the 
running  wheel  is  surrounded  by  a  series  of  combustion  chambers, 
which  alternately  are  filled  with  the  compressed  mixture,  fired, 
and  then  discharged  through  nozzles  on  the  blades  of  the  run- 
ning wheels.  This  of  course  requires  a  compressor  for  the 
compression  of  the  charge  and  a  rather  elaborate  system  of 
valves,  etc.  To  withstand  the  high  temperatures,  the  blades 
have  been  made  of  carborundum  or  other  refractory  material, 
or  steam  has  been  injected  to  reduce  the  final  temperature  at 
the  blading. 

The  accompanying  figure  shows  a  gas  turbine  described  by 
A.  W.  H.  Griepe  in  the  Gas  Engine.  The  rotating  member 
(Fig.  1)  is  similar  to  that  used  in  a  reaction  type  steam  turbine 
with  the  blades  distributed  in  four  equally  spaced  groups  around 
the  periphery  of  the  wheel.  Each  group  occupies  one-eighth  of 
the  circumference.  On  the  inside  of  the  rotor  spider,  carrying 
the  blades,  is  a  valve  band  R  which  acts  as  an  admission  and 
cut-off  valve  between  the  explosion  chamber  and  the  fuel-air 
supply.  The  inner  stationary  element  or  "Stator"  contains  the 
four  explosion  chambers  E-E-E-E,  the  air  chamber,  and  the  fuel 
chamber,  the  fuel  and  air  chambers  being  arranged  in  the  form 
of  rings  around  the  shaft.  Compressed  air  enters  the  air 
chamber  from  the  storage  tank  at  from  45  to  74  pounds  per 
square  inch,  and  the  gas  from  the  fuel  chamber  enters  at  prac- 
tically atmospheric  pressure.  The  turbine  is  in  duplicate  with 


HEAT  ENGINES 


23 


24  HEAT  ENGINES 

two  sets  of  nozzles  and  explosion  chambers,  so  that  when  one 
side  has  been  ignited  and  is  expanding,  the  explosion  chambers 
on  the  other  side  of  the  wheel  are  taking  in  a  charge  of  explosive 
mixture.  This  gives  approximately  a  constant  turning  effort  on 
the  turbine  wheel.  The  nozzles  leading  out  to  the  wheel  blades 
from  the  explosion  chambers  E-E-E-E  are  staggered  on  opposite 
sides  of  the  wheel,  the  nozzles  on  the  right  being  turned  one- 
eighth  of  a  revolution  from  those  on  the  left,  or  so  that  they  lie 
between  the  nozzles  on  the  left. 

In  Fig.  1,  the  wheel  is  in  a  position  where  the  nozzles  leading 
from  the  explosion  chamber  to  the  wheel  bades  are  closed  at  the 
outer  end,  and  where  the  ring  R  has  opened  the  admission  from 
the  fuel  and  air  supply  into  the  explosion  chambers.  (On  the 
near  side.)  The  compressed  air  enters  through  the  passage  in- 
dicated by  the  curved  arrows,  and  in  entering  acts  as  an  injector 
in  drawing  the  fuel  in  through  the  small  straight  nozzle  in  the 
center  of  each  valve.  (Shown  by  the  straight  arrows.)  This 
continues  until  the  wheel  has  revolved  into  the  position  shown 
in  Fig.  3. 

In  Fig.  3  it  will  be  seen  that  the  ring  valve  R  has  closed  the 
passage  between  the  air  and  fuel  supply,  and  the  explosion 
chamber,  and  also  that  the  nozzles  are  now  open  between  the 
explosion  chamber  and  the  turbine  blades.  The  valve  R  closes 
communication  between  the  explosion  chamber  and  fuel  supply 
an  instant  before  the  nozzles  are  opened  to  the  blades.  At  this 
instant  the  charge  is  ignited  and  expands.  The  ring  R  now 
opens  one  side  of  the  air  chamber,  with  the  ends  of  the  nozzles 
still  open  and  before  the  gas  port  opens  to  the  chamber  E.  This 
allows  a  blast  of  pure  air  to  sweep  through  the  explosion 
chamber  E  and  cleans  out  the  burnt  gas  before  the  explosive 
mixture  enters  for  the  next  explosion..  The  cycle  of  events  is  as 
follows: 

1.  Ring  opens  to  compressed  air  which  blows  out  the  burnt 
gas  remaining  from  the  previous  explosion.  2.  Valve  opens 
and  admits  combustible  mixture  of  air  and  fuel  into  explosion 
chamber,  and  the  mixture  is  compressed  by  the  continued  flow 
of  compressed  air  into  the  chamber.  3.  Valve  entirely  closes 
explosion  chamber,  ignition  takes  place,  and  maximum  explosion 
pressure  is  reached.  4.  Nozzle  is  opened,  and  the  gas  escapes 
and  expands  into  the  blades  of  the  running  wheel  producing 
power.  After  the  expansion  the  same  cycle  is  repeated.  An 
experimental  turbine  of  this  type  produced  from  85  to  90  horse- 


HEAT  ENGINES  25 

power  at  2,500  revolutions  per  minute,  the  efficiency  being 
approximately  20  per  cent. 

In  starting,  the  pressure  on  the  fuel  was  about  3  pounds,  but 
after  a  short  run,  the  nozzles  acted  as  an  injector  and  sucked  the 
fuel  into  the  explosion  chamber  making  a  carburetor  unneces- 
sary. A  heating  coil  in  the  base  was  used  to  assist  vaporization. 
It  is  claimed  that  the  combustion  never  was  the  cause  of  any 
trouble. 

The  rotating  blade  sections  were  of  cast  iron,  and  were 
inserted  in  the  rotor,  and  on  the  experimental  tests  have  stood 
up  well  although  it  is  possible  that  they  would  not  be  so 
satisfactory  in  long  continued  practical  service.  The  thickness 
ranges  from  y%  inch  near  the  edge  to  %  near  the  center,  and 
fringing  or  abrasion  only  occurred  at  points  where  the  core  left 
a  thin  edge.  It  would  seem,  however,  that  a  more  refractory 
substance  would  be  necessary  for  a  commercial  turbine,  for  if  a 
thin  edge  frayed  out  in  so  short  a  time  it  would  not  take  long 
to  go  through  a  plate  only  ]/$  inch  thick. 


CHAPTER  II 
WORKING  CYCLES 

(24)  Requirements  of  the  Engine. 

In  order  that  an  internal  combustion  engine  shall  operate 
and  develop  power  continuously  the  following  routine  of  events 
must  occur  in  the  cylinder  in  the  following  order,  no  matter 
what  the  type  of -engine. 

(1)  The  cylinder  must  be  filled  with  a  combustible  mixture 
of  air  and  gaseous  fuel  at  as  nearly  atmospheric  pressure  as 
possible. 

(2)  The  mixture  must  be   compressed  in   order  to   develop 
the  value  of  the  fuel. 

(3)  Ignition  must  take  place  at  the  end  of  the  compression 
stroke  or  at  the  highest  point  of  compression. 

(4)  Complete  combustion  of  the  fuel  must  follow  the  ignition 
of   the   charge,  with   an  increase   of  temperature   and  pressure 
which  will  act  on  the  piston  to  the  end  of  the  power  stroke. 

(5)  After  the  piston  has  completed  the  working  stroke  the 
products  of  combustion  must  be  ejected  from  the  cylinder  com- 
pletely to  make  way  for  the  admission  of  the  new  combustible 
mixture. 

With  the  exception  of  the  Diesel  engine  which  (1)  fills  the 
cylinder  with  pure  air  without  the  fuel,  and  (2)  injects  the  fuel 
after  compression,  all  internal  combustion  engines  not  only  per- 
form each  of  these  operations  but  proceed  with  events  in  the 
order  given  as  well.  The  accomplishment  of  the  five  acts  is 
called  a  "cycle  of  events,"  or  a  "CYCLE,"  and  the  series  is  per- 
formed in  different  ways  in  different  types  of  engines.  In  the 
operation  of  the  engine,  the  series  of  events  occur  over  and  over 
again,  always  in  the  same  order,  1-2-3-4-5,  1-2-3-4-5,  1-2-2-3-4-5, 
etc.  The  five  events  are  generally  given  in  terms  of  the  num- 
ber of  strokes  of  the  piston  taken  to  accomplish  the  complete 
routine,  thus  a  two  stroke  cycle  engine  performs  the  series  in 
two  strokes,  and  a  four  stroke  cycle  engine  in  four  strokes,  and 
so  on. 

In  order  to  obtain  the  benefits  of  high  compression,  perfect 

26 


CYCLES  27 

scavenging  of  the  products  of  combustion  from  the  cylinder  and 
perfect  mixtures,  a  great  variety  of  engines  have  been  developed 
in  which  the  number  of  strokes  taken  to  accomplish  the  five 
events  varies.  In  some  engines  the  cycle  is  accomplished  in 
two  strokes,  in  other  engines  it  is  accomplished  in  six  strokes, 
but  in  the  great  majority  of  cases  the  cycle  is  performed  in 
either  two  or  four  strokes,  and  as  these  are  by  far  the  most 
common  routines,  we  will  confine  our  description  to  engines  of 
these  types. 

(25)  Four  Stroke  Cycle  Engine. 

The  four  stroke  cycle  engine,  some  times  improperly  called 
the  "four  cycle"  engine  is  the  most  widely  used  type  for  all 
classes  of  service,  except  possibly  for  marine  work.  Its  ex- 
tended use  is  due  to  its  superior  scavenging,  high  efficiency  and 
reliability,  although  it  is  somewhat  more  complicated  than  the 
two  stroke  cycle  type.  Its  ability  to  function  properly  under  a 
wide  variation  of  speed  has  driven  the  two  stroke  cycle  type 
out  of  the  automobile  field,  and  its  many  admirable  character- 
istics have  cut  a  wide  swath  in  the  marine  field,  the  stronghold 
of  the  two  stroke  cycle  type. 

A  four  stroke  cycle  engine  performs  the  cycle  of  events  in 
four  strokes  or  two  revolutions,  only  one  of  the  strokes  being  a 
power  of  working  stroke.  In  a  single  cylinder  engine  the  ex- 
plosion in  the  working  strokes  supplies  enough  power  to  the 
fly-wheel  to  carry  the  engine  and  its  load  through  the  remain- 
ing three  strokes.  Thus  the  energy  stored  in  the  fly  wheel  is 
sufficient  to  carry  not  only  the  load  during  the  idle  strokes  but 
to  "inhale"  and  compress  the  charge  as  well.  Due  to  the  long 
interval  that  exists  between  explosions,  they  are  corresponding 
heavy  and  are  productive  of  heavy  strains  in  the  engine  and  are 
the  cause  of  considerable  vibration. 

To  reduce  the  ill  effects  of  the  heavy  intermittent  blows,  the 
majority  of  automobile  and  stationary  engines  are  provided 
with  two  or  more  cylinders,  the  power  being  equally  divided 
among  them.  In  a  four  cylinder  engine,  there  are  four  times 
as  many  impulses  as  in  a  single  cylinder  engine  and  the  blow 
.  dealt  by  the  individual  cylinder  is  only  one-quarter  as  great. 
While  a  single  cylinder  engine  has  an  impulse  only  once  in 
every  other  revolution,  the  four  cylinder  has  two  impulses  in 
one  revolution.  Besides  the  advantages  gained  by  increasing 
the  impulses,  the  mechanical  balance  of  a  multiple  cylinder  en- 
gine is  always  better  than  that  of  a  single  and  is  also  much 


28 


CYCLES 


Fig.  4.  Diagrammatic  View  of  Four  Stroke  Cycle  Engine  with  the  Piston 
in  Various  Positions  Corresponding  with  the  Five  Events.  Diagram 
A — Suction.  Diagram  B — Compression.  Diagram  C — Ignition.  Dia- 
gram D — Working  Stroke.  Diagram  E — -Release.  Diagram  F — - 
Scavenging  Stroke. 


CYCLES  29 

lighter  in  weight  since  less  material  is  required  to  resist  shocks 
of  the  explosions. 

Engines  with  more  than  four  cylinders  have  "overlapping" 
impulses,  that  is  some  cylinder  on  the  engine  is  always  deliver- 
ing power,  for  before  one  cylinder  reaches  the  end  of  the  stroke, 
another  has  fired  its  charge  and  has  started  to  deliver  power. 
Thus  the  impulses  "overlap"  one  another,  and  the  result  is  an 
even  and  smooth  application  of  power  and  a  minimum  of  strain 
is  imposed  on  the  engine. 

Aeronautical  and  speed  boat  engine  builders  have  carried  the 
multiple  cylinder  idea  to  an  extreme  because  of  the  nature  of 
their  work.  Eight  cylinder  aeronautical  engines  are  very  com- 
mon and  there  are  several  built  having  sixteen  cylinders.  The 
latter  type  of  engine  gives  eight  impulses  per  revolution.  To 
avoid  a  great  multiplicity  of  cylinders,  and  to  save  on  floor 
space,  the  great  majority  of  heavy  duty  stationary  engines  are 
built  double  acting,  that  is  an  explosion  occurs  alternately  in 
either  end  of  the  cylinder.  In  effect,  a  double  acting  cylinder 
is  the  same  thing  as  a  two  cylinder  single  acting  engine,  as 
it  gives  twice  the  number  of  impulses  obtained  with  a  single 
acting  cylinder. 

The  order  in  which  the  events  occur  in  a  four  stroke  cycle 
engine  is  as  follows: 

STROKE  1.  First  outward  stroke  of  the  piston  causes  a  par- 
tial vacuum  in  the  combustion  chamber  thus  drawing  a  charge 
of  combustible  gas  into  the  cylinder  through  the  open  inlet  valve. 
The  exhaust  valve  is  closed.  See  diagram  A  in  Fig.  4.  (Suction 
Stroke.) 

STROKE  2.  Inlet  valve  closes  at  the  end  of  the  suction 
stroke  and  the  piston  starts  on  the  inward  stroke  compressing 
the  charge  in  the  combustion  chamber.  See  diagram  B.  (Com- 
pression Stroke.)  At  the  end  of  the  compression  stroke,  or  a 
little  before,  the  spark  "S"  occurs  causing  the  ignition  of  the 
charge.  See  diagram  C. 

STROKE  3.  Working  Stroke.  As  the  pressure  is  now  estab- 
lished in  the  cylinder,  the  piston  moves  down  on  the  working 
stroke  forcing  the  crank  around  against  the  load  and  supplying 
sufficient  energy  to  the  fly  wheel  to  carry  the  engine  through 
the  three  idle  strokes.  See  diagram  D.  When  the  piston  reaches 
the  end  of  the  working  stroke,  or  a  little  before,  the  exhaust 
valve  opens  to  reduce  the  pressure  and  to  allow  the  greater  part 
of  the  burnt  gas  to  escape.  See  diagram  E. 

STROKE  4.  Scavenging  Stroke.  The  exhaust  valve  remains 
open  and  the  inwardly  moving  piston  expels  the  remainder  of 


30  CYCLES 

the  burnt  gas  through  the  exhaust  valve,  clearing  the  cylinder 
for  the  next  fresh  charge  of  mixture.  See  diagram  F.  The 
next  stroke  is  the  suction  stroke  explained  under  "Stroke  1." 

In  all  of  the  diagrams  the  crank  is  supposed  to  turn  in  a 
right  handed  direction  as  indicated  by  the  arrow,  the  piston 
moving  in  the  direction  shown  by  the  arrow  under  the  piston 
head.  The  valves  are  operated  by  cams  on  an  intermediate 
shaft  known  as  the  "cam  shaft."  As  the  valves  go  through 
their  series  of  movements  in  two  revolutions  of  the  crank  shaft, 
and  as  the  cam  shaft  must  perform  all  of  these  operations  in  one 
revolution,  it  is  evident  that  the  cam  shaft  must  run  at  exactly 
one-half  the  crank-shaft  speed.  This  change  of  speed  is  accom- 
plished by  means  of  gearing  between  the  cam  shaft  and  crank- 
shaft from  which  the  cam  shaft  is  driven. 

In  some  engines,  notably  the  Diesel  engine,  pure  air  is  drawn 
into  the  cylinder  on  stroke  No.  1  instead  of  the  entire  mixture. 
Fuel  is  supplied  in  this  type  immediately  after  the  end  of  the 
compression  stroke. 

While  an  electric  spark  is  shown  as  the  igniting  medium  in 
the  diagrams,  the  ignition  is  sometimes  performed  by  a  hot 
tube,  or  simply  by  the  heat  of  the  compression  as  in  the  Diesel 
engine. 

In  the  sliding  sleeve  type  of  four  stroke  cycle  motor,  the 
poppet  or  lifting  type  of  valve  as  shown  in  Fig.  4,  is  replaced 
by  a  peculiar  type  of  slide  valve  similar  in  action  to  the  slide 
valves  used  on  steam  engines,  except  that  it  is  cylindrical  in 
form  and  entirely  surrounds  the  piston.  While  there  is  a  change 
in  the  form  of  the  valve,  and  in  a  number  of  small  details,  the 
gases  are  drawn  into  the  cylinder,  compressed,  ignited,  and  re- 
leased in  exactly  the  same  way  and  in  the  same  rotation,  as 
in  the  poppet  valve  engine  just  described.  A  description  of  the 
Knight  engine  which  is  the  most  prominent  example  of  the  slide 
sleeve  motor  will  be  found  in  a  succeeding  chapter.  Since  the 
success  of  the  slide  valve  type  has  been  acknowledged  by  many 
prominent  automobile  manufacturers,  there  have  been  several 
similar  types  placed  on  the  market,  some  with  two  sleeves  and 
some  with  one,  but  in  all  cases  the  designers  have  had  but  two 
points  in  view,  that  is  quiet  running  and  free  passages. 

(26)  Two  Stroke  Cycle  Engine. 

Two  stroke  cycle  engines  perform  the  five  events  of  aspiration 
(suction),  compression,  ignition,  expansion  and  release  in  two 
strokes  or  one  revolution.  Providing  that  these  events  are  per- 


CYCLES 


31 


formed  as  efficiently  as  in  the  four  stroke  cycle  engine,  it  is 
evident  that  with  equal  cylinder  capacity,  the  two  stroke  cycle 
engine  would  have  twice  the  output  of  a  four  stroke  cycle  since 
it  gives  twice  the  number  of  impulses  per  revolution.  Un- 
fortunately it  is  impossible  to  attain  twice  the  output  of  the 
four  stroke  cycle  type  with  the  small  two  stroke  engines  built 
at  the  present  time  because  of  their  imperfect  scavenging  and 
poor  fuel  economy.  In  the  larger  two  stroke  engines,  the  pumps 
and  blowers  used  for  scavenging  the  cylinders  consume  a  con- 
siderable percentage  of  the  output. 

A  general  classification  of  the  two  stroke  cycle  engine  is  not 
so  simple  a  matter  as  that  of  the  four  stroke  because  of  the 


DIAGRAM  A. 

TTR5T-  STTTOKE' 


DIAGRAM  C- 

SECOND  STROKE 


Fig.   5. 


Diagram   of  Two   Port — Two   Stroke    Cycle    Engine,    Showing  the 
Events    in   the   Crank-Case   and   Cylinder. 


differences  in  construction  of  large  and  small  sizes.  This  dif- 
ference between  the  large  stationary  engine  and  the  small  type 
commonly  used  on  boats  is  due  to  the  efforts  of  the  builders 
of  the  large  engine  to  obtain  great  fuel  economy,  while  the 
chief  endeavors  of  the  builders  of  small  engines  is  to  build  a 
simple  and  reliable  engine  for  the  use  of  inexperienced  persons. 
While  the  smaller  type  of  two  stroke  engine  (less  than  25  horse- 
power) has  not  been  used  in  stationary  practice  to  any  extent, 
owing  to  the  defects  just  named,  or  on  automobiles,  it  has  been 
widely  used  on  motor  boats,  a  service  for  which  it  is  peculiarly 
adapted.  Its  extended  use  on  boats  is  due  to  the  fact  that  in 
such  service  it  runs  at  practically  a  constant  speed  and  works 


32  CYCLES 

against  a  steady  load,  the  conditions  that  are  most  favorable  to 
the  type.  With  automobiles  where  the  motor  speed  is  constantly 
varying,  as  well  as  the  load,  this  type  of  motor  is  not  flexible 
enough  to  meet  the  continually  varying  conditions. 

The  small  two  stroke  motors  are  divided  into  two  principal 
classes,  the  two  port  and  three  port  type,  depending  on  the 
method  by  which  the  charge  is  transferred  to  the  cylinder.  No 
valves  are  used  in  the  cylinders  of  either  type  for  the  admis- 
sion or  release  of  the  gases.  As  the  two  strokes  of  the  cycle 
are  the  compression  stroke  and  working  stroke,  it  is  evident 
that  the  charge  must  be  introduced  into  the  cylinder  by  means 
other  than  by  the  suction  of  the  piston  and  at  a  time  when  there 
is  no  pressure  in  the  cylinder.  This  is  accomplished  by  a  pre- 
liminary compression  of  the  charge  in  the  crank  case  which 
places  the  mixture  under  sufficient  pressure  to  force  it  into  the 
cylinder  at  the  end  of  the  working  stroke  and  at  the  same  time 
to  displace  the  burnt  gases  left  from  the  previous  explosion.  It 
should  be  noted  that  the  incoming  mixture  is  a  substitute  for 
both  the  suction  and  scavenging  strokes  of  the  four  stroke  cycle 
engine. 

A  diagrammatic  view  of  a  two  port,  two  stroke  cycle  engine 
is  shown  by  Fig.  5,  in  which  P  is  the  piston,  C  the  crank  case, 
I  the  transfer  port,  V  the  inlet  valve,  E  the  exhaust,  and  S  the 
spark  plug  for  igniting  the  charge.  It  should  be  noted  that 
there  are  no  valves  in  the  cylinder  and  only  three  moving  ports. 
The  cycle  of  events  for  the  two  port  type  is  as  follows: 

STROKE  1.  We  will  consider  the  piston  to  be  moving  up  on 
the  compression  stroke  as  shown  in  view  (A),  compressing  the 
mixture  in  the  combustion  chamber  D.  While  moving  upwards 
in  the  direction  of  the  arrow,  the  piston  creates  a  vacuum  in 
the  crank  case  C  drawing  fresh  mixture  into  the  crank  case. 
The  piston  at  this  time  is  covering  the  opening  of  the  transfer 
port  I  and  the  exhaust  port  E  so  that  the  compressed  mixture 
in  the  cylinder  cannot  escape.  On  reaching  the  end  of  the  com- 
pression stroke,  a  spark  occurs  at  S  which  drives  the  piston 
down  and  turns  the  crank  towards  the  right  as  shown  by  the 
arrow. 

STROKE  2.  When  the  piston  uncovers  the  exhaust  port  E  on 
its  downward  working  stroke  as  shown  by  view  B,  the  exhaust 
gases  being  under  pressure  rush  out  into  the  atmosphere  as 
shown  by  the  arrows,  and  relieve  the  pressure  in  the  cylinder. 
Some  of  the  burnt  gas  remains  in  the  cylinder  at  atmospheric 
pressure  as  there  is  no  scavenging  action  up  to  this  point.  While 
the  piston  has  moved  down  on  the  working  stroke  it  has  com- 


CYCLES  33 

pressed  the  mixture  in  the  crank  case  ready  for  admission  to 
the  cylinder.  The  valve  V  prevents  the  escape  of  the  gas  dur- 
ing the  compression. 

On  reaching  the  end  of  the  stroke  the  piston  uncovers  the 
transfer  port  which  allows  the  compressed  mixture  in  the  crank 
case  to  rush  into  the  cylinder  through  I,  as  shown  by  view  C. 
Owing  to  the  shape  of  the  deflector  plate  Z  on  the  piston  head, 
the  stream  of  mixture  issuing  from  I  is  thrown  up  toward  the 
top  of  the  cylinder,  as  shown  by  the  arrows,  and  consequently 
sweeps  the  remainder  of  the  burnt  gas  before  it  through  the 
exhaust  port  E.  In  this  way  the  fresh  mixture  from  the  crank 
case  scavenges  the  cylinder  and  fills  it  in  one  operation.  Being 
filled  with  gas,  the  piston  now  moves  up  on  the  compression 
stroke  for  the  next  explosion  as  shown  by  view  A. 

Unfortunately  the  scavenging  action  of  the  incoming  gas  is 
not  complete  for  the  whirling  motion  of  the  charge  causes  it 
to  mix  with  the  residual  gas  to  a  certain  extent  which,  of  course, 
reduces  the  heating  effect  of  the  fuel  and  reduces  the  power 
output.  Another  factor  that  reduces  the  output  of  this  type 
of  engine  is  the  loss  of  explosive  mixture  through  the  ex- 
haust port  at  low  engine  speeds  with  an  open  throttle.  In 
this  case,  the  piston  speed  being  low,  part  of  the  mixture  has 
time  to  pass  over  the  deflector  plate  and  through  the  exhaust 
opening  before  the  piston  closes  the  exhaust  port.  At  very 
high  speeds  the  charge  is  diluted  by  a  considerable  quantity  of 
burnt  gas  which  has  not  had  time  to  escape  through  the  port 
causing  a  further  loss  of  power.  With  the  throttle  nearly 
closed  on  a  light  load,  the  impact  of  the  incoming  mixture  is 
so  slight  that  the  percentage  of  exhaust  gas  left  in  the  cylinder 
is  very  high.  This  dilution  is  so  great  that  with  moderately 
low  speeds  (easily  within  the  capacity  of  the  four  stroke  cycle 
engine)  it  is  either  impossible  to  ignite  the  charge  or  it  is  im- 
possible to  ignite  two  in  succession. 

In  marine  service  where  the  loads  are  constant,  and  the 
speeds  fairly  uniform,  there  is  but  little  trouble  from  the  last 
mentioned  source,  and  as  the  fuel  is  usually  a  smaller  item 
than  the  repair  bill,  the  simplicity  of  the  small  two  stroke  en- 
gine with  its  freedom  from  mechanical  troubles  usually  gives 
satisfactory  results  in  the  hands  of  the  novice. 

(27)  Three  Port— Two  Stroke  Cycle  Engine. 

The  principal  difference  between  the  three  port  and  two  port 
types  of  the  two  stroke  cycle  engine  is  in  the  manner  in  which 


34 


CYCLES 


the  charge  is  admitted  to  the  crank  case  for  the  initial  compress- 
ion. In  the  two  port  motor,  as  previously  described,  the  check 
valve  "V"  opens  to  admit  the  charge,  and  closes  during  its  com- 
pression in  order  to  prevent  its  escape  through  the  opening 
by  which  it  was  admitted  to  the  cylinder.  With  the  three  port 
type  there  is  no  check  valve  in  the  crank  case,  the  admission 
and  the  retention  of  the  charge  being  controlled  by  the  move- 
ment of  the  piston  in  practically  the  same  way  that  the  piston 
controls  the  opening  and  closing  of  the  exhaust  and  transfer 
ports  in  the  cylinder. 


Fig.  6. 


Fig.   7. 


Figs.    6-7.     Diagram   of   Three    Port — Two    Stroke    Cycle    Engine   in  Two 

Positions. 

By  the  piston  control  of  the  gases  in  the  crank  case,  the  valve 
is  eliminated,  which  makes  one  less  moving  part  to  cause  trou- 
ble and  expense,  and  permits  the  use  of  the  same  type  of  car- 
buretor that  is  used  on  the  four  stroke  cycle  engine.  As  the 
check  valve  opens  and  closes  at  a  high  speed,  (twice  that  of  the 
valves  on  a  four  stroke  cycle  engine),  there  is  considerable 
wear  on  the  valve  seats  due  to  the  continuous  banging,  which 
results  finally  in  a  loss  of  the  initial  compression.  When  the 
initial  compression  is  reduced  in  this  way  the  engine  loses 
power  because  of  the  reduction  of  the  charge  in  the  cylinder. 

While  the  three  port  type  is  free  from  valve  leakage  troubles, 


CYCLES 


35 


it  has  a  steady  loss  due  to  the  high  vacuum  that  exists  in  the 
crank  chamber  when  the  piston  is  on  its  upward  stroke.  This 
vacuum  drags  against  the  piston  and  absorbs  a  considerable 
amount  of  power  until  the  piston  reaches  the  upper  end  of 
the  stroke.  At  this  point  the  inlet  port  is  opened  and  the 
vacuum  is  broken  by  the  rush  of  the  mixture  through  the  in- 
let port.  Besides  the  power  loss,  the  vacuum  has  a  bad  effect 
on  the  lubrication  of  the  main  crank  shaft  bearing. 

Described  by  strokes,  the  cycle  of  events  in  the  three  port, 
two  stroke  cycle  engine  is  as  follows: 


Elevation  of  Fairbanks-Morse  Three-Port  Two   Stroke  Marine  Motor   Show- 
ing Warming  Device  for   Carburetor  Air. 

STROKE  1.  In  Fig.  6,  the  piston  is  shown  at  the  end  of  the 
compression  stroke  with  ignition  taking  place  in  the  combustion 
chamber  C.  The  pressure  due  to  the  expansion  drives  the  piston 
down  on  the  working  stroke  at  the  same  time  causing  the  initial 
compression  of  the  mixture  in  the  crank  case  as  shown  by  Fig. 
7.  The  gas  in  the  crank  case  cannot  escape  during  compression 
as  the  inlet  port  A  is  covered  by  the  piston. 

(a)  As  the  piston  descends,  its  upper  edge  uncovers  the  ex- 
haust port  D,  allowing  the  greater  portion  of  the  exhaust  gases 
to  escape  and  reduces  the  pressure  in  the  cylinder  to  that  of 
the  atmosphere. 


36  CYCLES 

(b)  Descending  a  little  farther,  the  top  of  the  piston  uncovers 
the  opening  of  the  transfer  port  B,  allowing  the  compressed 
gases  in  the  crank  case  to  enter  the  cylinder  as  shown  by  the 
arrows.  These  gases,  guided  by  the  deflector  plate  on  the  top 
of  the  piston  are  thrown  upwardly,  as  shown  by  the  arrows,  and 
sweep  the  residual  burnt  gases  before  them  through  the  exhaust 
port.  The  cylinder  is  now  filled  with  the  combustible  mixture 
ready  for  compression. 

STROKE  2.  The  piston  now  moves  up  on  the  compression 
stroke,  compressing  the  charge  in  the  cylinder  and  at  the  same 
time  creates  a  vacuum  in  the  crank-case.  Just  before  the  piston 
reaches  tne  end  of  the  exhaust  stroke,  the  lower  edge  of  the 
piston  uncovers  the  inlet  port  A  (See  Fig.  7),  which  allows  the 
mixture  from  the  carburetor  to  flow  into  the  partial  vacuum 
and  fill  the  crank  case  ready  for  the  next  initial  compression. 
When  the  end  of  the  stroke  is  reached,  the  charge  in  the  com- 
bustion chamber  C  is  fired  and  the  cycle  is  repeated.  It  should 
be  noted  that  the  incoming  gas  and  the  initial  compression  are 
controlled  entirely  by  the  action  of  the  lower  edge  of  the  piston 
on  the  inlet  port  A  . 

(28)  Reversing  Two  Cycle  Motors. 

As  the  admission  and  exhaust  in  the  two  stroke  cycle  engine 
each  occur  once  per  revolution,  'and  are  controlled  directly  by 
the  piston  position  at  opposite  ends  of  the  stroke,  it  is  evi- 
dent that  the  direction  of  rotation  is  not  affected  by  gas  con- 
trol or  valve  timing,  as  in  the  case  of  the  four  stroke  cycle  en- 
gine. The  factor  that  does  determine  the  direction  of  rotation 
in  the  two  stroke  engine  is  the  time  at  which  ignition  occurs 
in  regard  to  the  angular  position  of  the  crank.  By  changing 
the  relation  between  the  crank  position  at  the  end  of  the  com- 
pression stroke  and  the  time  at  which  the  spark  occurs,  it  is 
possible  to  reverse  the  engine  even  when  it  is  running. 

Should  the  engine  be  standing  still  in  the  position  shown  by 
Fig.  6,  with  the  crank  on  the  dead  center,  when  ignition  oc- 
curred, there  would  be  no  more  tendency  to  turn  the  crank 
to  the  right  than  to  the  left,  providing  of  course,  that  there  was 
no  effect  from  the  momentum  of  a  revolving  fly  wheel.  If  igni- 
tion occurred  with  the  crank  inclined  ever  so  little  toward  the 
right,  the  pressure  of  the  piston  would  force  the  crank  down- 
wards in  a  right  handed  direction.  If  the  crank  were  inclined 
to  the  left,  the  tendency  would  be  for  left  handed  rotation. 

If  the  ignition  system  were  arranged  so  that  the  spark  oc- 


CYCLES 


37 


curred  when  the  crank  was  inclined  towards  the  right  every 
time  that  the  piston  came  up  on  the  compression  stroke,  we 
should  have  continuous  rotation  in  a  right  hand  direction.  By 
shifting  the  sequence  of  the  spark  so  that  it  occurred  with  the 
crank  on  the  left  we  would  cause  the  engine  to  stop  and  re- 
verse to  left  handed  rotation.  This  is  exactly  the  method  used 
in  reversing  two  stroke  motors  in  practice,  the  change  in  the 


CYLINDER  HEAD 


WATER  BY  PASS 
TO  MANIFOLD 
WATER  JACKET 

INLET  AND  EXHAUST 

MANIFOLD 

EXHAUST  PORT 


WATER  BY-PASS  Jj 
TO  CYLINDER  HEAD 


TRANSFER  PORT 
PISTON  RING 

PISTON  PIN 
PISTON  PIN  BUSHING 
OIL  GROOVE 

PLEATED  SCREEN 
IN  TRANSFER  PASSAGE 
CONNECTING  ROD 
CRANKSHAFT 
OJPPEB  CRANK  CAS 


CONNECTING 
ROD  BUSHING 

HIPPER  HALF 
LOWER  HALF 


DUCT  FROM 
OIL  RING  TO  CRANK 

LOWER  CRANK  CASE 
CONNECTING  ROD  CAP 
L  SCOOP 


Fig.    F-9.      Cross    Section    of    Fairbanks-Morse    Three    Port— Two    Stroke 
Cycle   Engine,   with    Parts   Named. 

ignition  being  accomplished  by  advancing  or  retarding  the 
mechanism  that  dispatches  the  spark  ("Timer"  or  "Commu- 
tator"). 

This  is  an  advantage  not  possessed  by  the  four  stroke  cycle 
engine  of  the  ordinary  type,  as  the  cams  and  valve  mechanism 
require  reversal  as  well  as  a  reversal  of  the  ignition  system. 
This  relation  between  the  valve  action  and  rotation  in  a  four 
stroke  cycle  engine  may  be  illustrated  by  the  following  example. 


38  CYCLES 

Consider  the  piston  at  the  end  of  the  compression  stroke  in  an 
engine  designed  for  right  hand  rotation.  After  ignition,  under 
the  proper  conditions,  the  piston  would  descend  turning  the 
crank  to  the  right  until  it  reached  the  bottom  of  the  stroke,  at 
which  point  the  exhaust  valve  would  open  and  relieve  the  press- 
ure in  the  cylinder. 

Let  us  now  consider  an  attempt  at  reversing  the  engine  by 
causing  the  spark  to  occur  before  the  piston  reached  the  end 
of  the  compression  stroke  with  the  crank  still  inclined  toward 
the  left.  In  this  case  the  piston  would  force  the  crank  down 
in  a  left  hand  direction  until  it  reached  the  end  of  the  stroke. 
The  exhaust  valve  would  not  open  to  relieve  the  pressure,  as  the 
exhaust  cam  would  be  moving  away  from  the  valve  rod  in- 
stead of  toward  it.  Should  the  crank  swing  a  little  past  the 
dead  center,  because  of  its  momentum,  the  inlet  valve  would  be 
opened  instead  of  the  exhaust,  and  the  contents  of  the  cylinder 
would  shoot  through  the  intake  pipe  and  carburetor.  This 
would  bring  matters  to  a  close  as  far  as  rotation  was  concerned. 

The  opening  of  the  inlet  valve  on  the  reversed  working  stroke 
would  occur  as  the  inlet  valve  closes  one  stroke,  or  one-half 
revolution,  before  the  end  of  the  compression  stroke.  As  the 
engine  turned  backward  one-half  revolution,  the  inlet  cam  would 
again  be  brought  into  contact  with  the  inlet  valve  rod,  opening 
the  valve  and  allowing  the  burned  gases  to  pass  through  the 
carburetor.  Should  the  pressure  be  sufficiently  reduced  by  in- 
let valve  to  allow  the  piston  to  reach  the  end  of  the  second 
stroke,  it  would  start  on  the  third  stroke  by  inhaling  a  "charge" 
of  burnt  gas  through  the  exhaust  valve  which  would  now  be 
open. 

(29)  Scavenging  Engines. 

As  the  piston  does  not  sweep  out  all  the  cylinder  volume  be- 
cause of  the  space  left  at  the  end  of  the  cylinder  for  compression, 
more  or  less  burned  gas  remains  in  the  combustion  chamber 
which  dilutes  the  active  mixture  taken  in  on  the  suction  stroke. 
Not  only  are  the  residual  gases  useless  in  generating  heat  but 
they  also  occupy  a  considerable  space  in  the  cylinder  that  might 
otherwise  be  filled  with  a  heat  producing  mixture.  Their  dilut- 
ing effect  also  prevents  the  complete  combustion  of  a  certain 
percent  of  the  fuel  actually  taken  into  the  cylinder  for  which 
the  burnt  gas  is  incapable  of  supporting  combustion. 

The  amount  of  burnt  gas  remaining  in  the  cylinder  depends 
upon  the  cycle  of  the  engine  and  also  upon  the  valve  timing 


CYCLES  39 

and  size  of  the  exhaust  piping.  In  the  four  stroke  cycle  en- 
gine the  volume  of  residual  gas  is  equal  to  the  volume  of  the 
combustion  chamber,  in  the  two  stroke  cycle  it  varies  from 
one-tenth  to  one-third  of  the  entire  cylinder  volume,  depend- 
ing on  the  load  and  speed.  With  correct  design  and  free  ex- 
haust passages,  the  gas  held  in  the  clearance  space  of  a  four 
stroke  cycle  engine  is  at  a  pressure  considerably  below  that 
of  the  atmosphere,  and  consequently  its  actual  volume  is  even 
less  than  the  volume  of  the  combustion  chamber. 

Many  systems  have  been  devised  for  the  purpose  of  clear- 
ing the  cylinder  of  burnt  gas  in  order  to  minimize  the  loss  of 
fuel  in  large  engines,  but  owing  to  their  complication  have  never 
been  successfully  applied  to  small  engines  of  the  automobile 
or  marine  types.  In  general,  the  "scavenging"  is  accomplished 
by  pumping  out  the  clearance  space  at  the  end  of  the  scaveng- 
ing stroke,  while  fresh  air  is  admitted  to  the  cylinder  through 
the  inlet  valves,  or  by  blowing  out  the  clearance  space  by  a 
blast  of  pure  air  furnished  from  an  air  pump  attached  to  the 
engine. 

There  have  been  several  systems  proposed  by  which  the  gas 
in  the  cylinder  is  withdrawn  by  the  inertia  of  the  exhaust  gas  in 
specially  designed  ejectors,  and  by  the  compression  of  fresh  air 
in  the  crank  case  of  the  engine.  The  former  system  known  as 
"organ  pipe  ejection,"  is  by  far  the  simplest  method  of  all  as 
the  ejector  is  simply  a  tube  without  moving  parts,  and  it  also 
possesses  the  additional  advantage  of  reducing  the  back  press- 
ure on  the  piston.  Unfortunately  these  advantages  are  obtained 
only  at  certain  loads,  and  with  certain  velocities  of  the  exhaust 
gases,  which  makes  it  impossible  to  obtain  even  approximately 
correct  scavenging  at  other  loads  and  speeds. 

When  air  pumps  are  used  for  scavenging,  a  great  percentage 
of  the  economy  obtained  is  offset  by  the  power  required  to 
operate  the  pumps.  In  addition  to  the  frictional  losses  of  the 
pumps,  are  the  increased  maintenance  charges  and  repair  bills. 


CHAPTER  III 
FUELS  AND  COMBUSTION 

(7)  Combustion. 

The  phenomenon  called  combustion  by  which  we  obtain  the 
heat  energy  necessary  for  the  operation  of  the  internal  combus- 
tion engine  is  a  chemical  combination  of  th^  air  with  the  fuel. 
This  process  results  in  heat  and  some  light  which  is  equal  in 
quantity  to  the  energy  required  to  separate  the  fuel  compound 
into  its  elements  or  to  build  it  up  in  its  present  form  from  the 
original  elements.  If  the  process  is  comparatively  slow,  the 
compound  is  called  a  fuel,  if  it  is  instantaneous  it  is  called  an 
explosive.  Some  substances  produce  mechanical  force  through 
an  instant,  without  the  evolution  of  much  heat,  due  to  the  dis- 
integration of  an  unstable  compound.  The  effect  of  the  latter 
type  of  which  dynamite  is  an  example  is  static,  that  is  to  say, 
it  is  not  capable  of  producing  power,  but  only  pressure.  For 
this  reason,  compounds  having  an  instantaneous  effect  without 
the  ability  to  produce  the  pressure  through  a  distance,  or  an 
expansion,  are  not  considered  as  suitable  fuels  for  a  heat  engine. 

A  fuel  is  essentially  a  substance  which  is  capable  of  generat- 
ing heat,  which  is  a  form  of  energy,  and  not  static  pressure.  The 
heat  engine  is  instrument  which  transforms  this  energy  into 
power  which  is  again  dissipated  into  heat  through  the  friction 
of  the  engine  itself  and  by  the  load  that  it  drives.  This  is  an 
illustration  of  the  physical  law  that  "energy  can  neither  be 
created  nor  destroyed,"  th'at  is,  the  heat  energy  developed  by 
the  fuel  is  converted  into  mechanical  energy  which  is  again 
transformed  into  heat  energy  through  friction. 

It  should  be  understood  that  fuel  belongs  to  that  class  of 
substances  that  will  not  burn  nor  evolve  energy  under  any 
temperature,  pressure,  or  shock,  without  an  outside  supply  of 
oxygen.  This  is  the  characteristic  property  of  all  fuels  used 
with  the  infernal  combustion  engine.  Each  element,  such  as 
carbon  and  hydrogen,  in  a  compound  fuel,  develops  a  certain 
definite  amount  of  heat  during  their  complete  combustion,  and 
at  the  close  of  the  process  certain  compounds  are  formed  that 

41 


42  FUELS 

represent  the  lowest  chemical  form  of  the  compound.  To  re- 
store the  products  of  combustion  to  their  original  form  as  fuel 
would  require  an  expenditure  of  energy  equal  to  that  given  out 
in  the  combustion. 

While  all  substances  that  are  capable  of  oxydization  or  com- 
bustion can  be  made  to  liberate  heat  energy,  it  does  not  follow 
that  all  of  them  can  be  successfully  used  as  fuels.  A  fuel  suit- 
able for  the  production  of  power  must  be  cheap,  accessible  and 
of  small  bulk,  and  must  burn  rapidly.  Such  fuels  must  also  be 
products  of  nature  that  require  no  expenditure  of  energy  in 
their  preparation  or  completion. 


Fig.    F-4.     Fairbanks-Morse    Producer    Plant    and    Engine,    Connected    for 

Operation. 

In  practical  work,  the  natural  fuels  are  coal,  mineral  oils, 
natural  gas,  and  wood,  which  are  compounds  of  the  elements 
carbon  and  hydrogen.  When  these  fuels  are  burned  to  their 
lowest  forms  the  products  of  combustion  consist  of  carbon 
dioxide  and  water,  the  first  being  the  result  of  the  oxydization 
of  carbon,  and  the  latter  a  compound  of  oxygen  and  hydrogen. 
In  solid  fuels,  such  as  coal,  a  portion  of  the  compound  consists 
of  free  carbon  and  the  remainder  of  a  compound  of  carbon  and 
hydrogen  known  as  a  HYDROCARBON.  In  liquid  fuels  there 
is  little,  if  any,  free  carbon,  the  greater  proportion  being  in  the 


FUELS  43 

form  of  a  hydrocarbon  compound.  Natural  gas  is  a  hydrocarbon 
compound. 

It  should  be  noted  that  a  definite  amount  of  oxygen  is  re- 
quired for  the  complete  combustion  of  the  fuel  elements,  and 
that  a  smaller  amount  of  oxygen  than  that  called  for  by  the 
fuel  element  results  in-  incomplete  combustion,  which  produces 
a  product  of  higher  form  than  that  produced  by  the  complete 
reduction.  The  product  of  incomplete  combustion  represents  a 
smaller  evolution  of  heat  than  that  of  the  complete  process, 
but  if  reburned  in  a  fresh  supply  of  oxygen  the  sum  of  the 
second  combustion  together  with  that  of  the  first  will  equal  the 
heat  of  the  complete  oxydization.  When  pure  carbon  is  uncom- 
pletely  burned  the  product  is  carbon  monoxide  (CO)  instead  of 
carbon  dioxide  (CO2). 

Carbon  completely  burned  to  carbon  dioxide  produces  14,500 
British  thermal  units  per  pound  of  carbon,  while  .the  incom- 
plete combustion  to  carbon  monoxide  evolves  only  4,452  British 
thermal  units,  or  less  than  one-third  of  the  heat  produced 
by  the  complete  combustion.  Theoretically  one  pound  of  car- 
bon requires  2.66  pounds  of  oxygen  to  burn  it  to  carbon  dioxide. 
On  supplying  additional  oxygen,  the  carbon  monoxide  may  be 
burned  to  carbon  dioxide  and  the  remainder  of  the  heat  may 
be  recovered,  or  10,048  British  thermal  units.  When  a  hydro- 
carbon, either  solid,  liquid  or  gaseous  is  burned  with  insufficient 
oxygen,  solid  carbon  is  precipitated  together  with  lower  hydro- 
carbons, and  tar.  In  an  internal  combustion  engine  the  pre- 
cipitated solid  carbon  is  evident  in  the  form  of  smoke. 

Since  the  carbon  and  hydrogen  elements  of  a  fuel  exist  in 
many  different  proportions  and  conditions  in  coal  and  oil,  differ- 
ent amounts  of  oxygen  are  required  for  the  consumption  of  dif- 
ferent fuels.  It  should  also  be  borne  in  mind  that  a  greater 
quantity  of  air  is  required  for  the  combustion  of  a  fuel  than 
oxygen,  as  the  air  is  greatly  diluted  by  an  inert  gas,  nitrogen, 
which  will  not  support  combustion.  Because  of  the  impos- 
sibility of  obtaining  perfectly  homogenous  mixtures  of  air  and 
the  fuel,  a  greater  quantity  of  air  is  used  in  practice  than  is 
theoretically  required. 

In  a  steam  engine  the  fuel  can  be  used  in  any  form,  solid, 
liquid,  or  gaseous,  but  in  an  internal  combustion  it  must  be 
in  the  form  of  a  gas  no  matter  what  may  have  been  the  form 
of  the  primary  fuel.  Fortunately  there  is  no  fuel  which  may 
not  be  transformed  into  a  gas  by  some  process  if  not  already 
in  a  gaseous  state,  The  petroleum  products  are  vaporized  by 


44  FUELS 

either  the  heat  of  the  atmosphere  or  by  spraying  them  on  a 
hot  surface.  Coal  is  converted  into  a  gas  by  distilling  it  in  a 
retort  or  by  incomplete  combustion.  The  heat  energy  developed 
by  a  gas  when  burning  in  the  open  air  depends  on  its  chemical 
combustion,  but  its  mechanical  equivalent  in  power  when 
burned  in  the  cylinder  of  the  engine  depends  not  only  upon 
its  composition  but  upon  the  conditions  under  which  it  is 
burned  as  stated  in  the  chapter  devoted  to  the  subject  of  heat 
engines. 

(8)     Gaseous  Fuels. 

While  the  calorific  values  of  the  different  gases  given  in 
the  accompanying  table  are  approximately  correct  for  gases 
burning  in  the  open  air  at  atmospheric  pressure  they  develop 
widely  different  values  in  the  cylinder  of  an  engine  because  of 
the  effects  of  compression  and  preheating.  The  table  serves, 
however,  as  an  index  to  the  relative  values  of  the  fuels  under 
ordinary  conditions  without  compression.  While  natural  gas 
has  nearly  eight  times  the  calorific  value  of  producer  gas  in 
the  open  air,  its  actual  heat  value  in  the  cylinder  is  only  about 

45  per  cent  greater.     While  acetylene  has  an  exceedingly  high 
calorific  value  and  explodes  five  times  as  fast  as  gasoline  gas, 
it  develops  only  20  per  cent  more  power  in  the  same  cylinder. 
Another  item  affecting  the  value  of  a  gas  is  the  rate  at  which 
it  burns,  which  is  in  part  a  characteristic  of  the  fuel  and  partly 
a  factor  of  the  conditions  under  which  it  is  burnt.     This  sub- 
ject is  treated  of  in  the  chapter  devoted  to  the  heat  engine. 

The  calorific  value  of  a  gas  may  either  be  computed  from  its 
chemical  composition  or  by  burning  it  in  an  instrument  known 
as  a  calorimeter.  A  gas  calorimeter  consists  of  a  small  boiler 
or  heating  tank  which  is  carefully  covered  with  some  non- 
conducting material  so  as  to  prevent  a  loss  of  heat  to  the  at- 
mosphere. The  gas  under  test  is  burned  in  the  boiler  whose 
extended  surface  catches  as  much  of  the  heat  as  possible  and 
transfers  it  to  the  water  in  the  boiler.  The  weight  of  the 
water  heated  and  its  temperature  are  taken  when  a  certain 
amount  of  the  gas  has  been  burned  (say  100  cubic  feet),  and 
from  this  data,  the  heat  units  per  cubic  foot  of  gas  are  com- 
puted. 

As  a  British  thermal  unit  is  the  amount  of  heat  required 
to  raise  the  temperature  of  one  pound  of  water  through  one 
Fahrenheit  degree  (at  about  39.1°  F.),  the  total  heat  per  cubic 
foot  of  gas  as  observed  by  the  calorimeter  is  equal  to  the  weight 


FUELS 


45 


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46  FUELS 

of  the  water  multiplied  by  its  use  in  temperature  in  degrees, 
divided  by  the  number  of  cubic  feet  of  gas  burned  in  the  calori- 
meter. Since  a  British  thermal  unit  is  equal  to  778  foot  pounds 
in  mechanical  energy,  its  mechanical  equivalent  is  equal  to  the 
number  of  British  thermal  units  multiplied  by  778. 

Another  difference  between  the  actual  and  theoretical  results 
obtained  is  that  due  the  perfect  combustion  in  the  calorimeter 
and  the  imperfect  combustion  in  the  engine.  Since  some  gases 
require  more  air  for  their  combustion  than  others,  less  of  the 
first  gas  will  be  taken  into  the  cylinder  on  a  charge  than  the 
latter,  which  tends  still  further  to  balance  the  heating  effect 
of  rich  and  lean  gases  in  the  cylinder. 

(9)  Gasifying  Coal. 

Coal  Gas  or  Illuminating  Gas  is  generated  by  baking  the  coal 
in  a  closed  retort  or  chamber  out  of  contact  with  the  air  so 
that  no  combustion  takes  place  either  complete  or  incomplete. 
The  hydrocarbon  gases  and  tars  are  set  free  from  the  coal  as 
permanent  gases  and  are  then  piped  to  a  gas  holder  after  going 
through  various  purifying  processes  to  remove  the  tars,  oils, 
moisture  and  dust.  The  free  or  solid  part  of  the  coal  remains 
in  the  retort  in  the  form  of  coke,  which  is  again  burned  for 
fuel. 

Because  of  its  high  carbon  content,  coal  gas  burns  with  a 
yellowish-white  flame  and  is  extensively  used  for  lighting  pur- 
poses, hence  the  name  illuminating  gas.  In  many  ways  coal 
gas  is  an  ideal  fuel  for  power  purposes  as  it  has  a  high  calorific 
value  (650-750  B.T.U.  per  cubic  ft.),  is  supplied  by  the  illumi- 
nating company  at  practically  a  constant  pressure,  and  is  uni- 
form in  quality.  Its  only  drawback  is  its  comparatively  high 
cost. 

This  gas  is  always  obtained  from  the  city  service  mains  as  its 
preparation  is  too  expensive  and  complicated  for  the  gas  en- 
gine owner.  Because  of  its  cost,  the  use  of  coal  gas  is  restricted 
to  small  engines. 

(10)  Water  Gas. 

Water  gas  is  made  by  blowing  air  through  a  thick  bed  of 
some  coal  that  is  low  in  hydrocarbons  until  the  coal  becomes 
incandescent,  the  gases  that  are  formed  are  allowed  to  escape 
to  the  atmosphere.  At  this  point  a  jet  of  steam  is  blown  into 
the  incandescent  bed,  which  is  broken  up  into  its  elements,  oxy- 
gen and  hydrogen,  by  the  heat  of  the  fuel,  As  there  is  no 


FUELS  47 

air  present  the  oxygen  combines  with  the  carbon  of  the  fuel 
to  form  carbon  monoxide  while  the  hydrogen  goes  free.  Both 
of  these  gases,  carbon  monoxide  and  hydrogen,  are  collected 
and  supplied  to  the  engine.  The  production  of  water  gas  is 
intermittent,  as  the  steam  blast  cools  down  the  fuel  bed,  and 
requires  further  blowing  before  more  steam  can  be  passed. 
While  this  gas  has  a  lower  heating  value  than  coal  gas,  it  is 
much  cheaper  to  make  and  all  of  the  coal  is  consumed  in  the 
process. 

Water  gas  is  high  in  hydrogen  and  is  too  "snappy"  for  gas 
engines;  the  hydrogen  places  a  limit  on  the  allowable  com- 
pression. 

For  each  thousand  feet  of  water  gas  generated,  approximately 
24  pounds  of  water  are  required. 

By  the  introduction  of  hydrocarbons  or  vaporized  oil,  illumi- 
nating value  is  given  to  water  gas,  this  process  is  called  car- 
buretion.  Carbureted  gas  is  not  usually  used  for  power,  as  it 
is  expensive,  and  is  not  proportionately  high  in  heating  value. 

(11)  Blast  Furnace  Gas. 

Many  steel  companies  are  utilizing  the  unconsumed  gas  of 
the  blast  furnaces  for  power. 

Blast  furnace  gas  is  of  very  low  calorific  value,  rarely  if 
ever,  exceeding  85  B.T.U.  per  cubic  foot.  This  allows  of  very 
high  compression,  which  greatly  increases  the  actual  power 
delivered  by  the  engine. 

A  smelter  produces  approximately  88,000  cubic  feet  of  gas 
per  ton  of  iron  smelted. 

Blast  furnace  gas  is  so  lean  that  it  cannot  be  burned  satis-. 
factorily  under  a  boiler;  the  high  compression  of  the  gas  en- 
gine makes  its  use  possible. 

(12)  Producer  Gas. 

Producer  gas  which  is  generated  by  the  incomplete  combus- 
tion of  fuels  in  a  deep  bed  is  the  most  commonly  used  gas  for 
engines  having  a  capacity  of  50  horsepower  and  over,  because 
of  the  simplicity  and  economy  of  its  production.  While  pro- 
ducer gas  has  been  obtained  from  practically  every  solid  fuel, 
of  which  coal,  coke,  wood,  lignite,  peat,  and  charcoal  are  ex- 
amples, the  fuel  most  generally  used  is  either  coal  or  coke. 
While  producer  gas  is  much  lower  in  calorific  value  than  either 
natural  or  illuminating  gas  it  gives  admirable  results  in  the  gas 
engine  and  is  a  much  cheaper  fuel  than  coal  gas  in  units  above 


48  FUELS 

50  horse-power  capacity.  The  fuel  is  completely  burned  to 
ash  in  the  producer  without  the  intermediate  coke  product  that 
exists  in  the  manufacture  of  coke. 

A  producer  consists  of  three  independent  elements  as  shown 
by  Fig.  F-6;  the  PRODUCER  or  generator  (A),  the  steam  boiler 
(B),  and  the  SCRUBBER  or  purifier  (C).  The  incandescent  fuel 
(F)  in  the  form  of  a  cone  lies  on  the  grate  bars  (G)  at  the 
lower  end  of  the  producer.  Above  the  burning  fuel  is  a  deep 
bed  of  coal  (D)  which  reaches  to  the  top  of  the  producer  at 
which  point  it  is  admitted  to  the  bed  through  the  charging 
valve  or  gate  (H).  The  gas  resulting  from  the  combustion 
in  the  producer  is  drawn  out  of  the  tank  through  the  gas  out- 
let pipe  (E)  by  the  suction  of  the  engine.  The  air  for  the 
combustion  is  drawn  up  through  an  opening  in  the  ash  pit 
(J)  by  the  engine. 

When  the  oxygen  of  the  air  strikes  the  incandescent  fuel 
on  the  grate  it  combines  with  a  portion  of  it  forming  carbon 
dioxide  (CO2)  which  is  an  incombustible  gas,  but  on  passing 
through  the  burning  fuel  above  this  point,  one  atom  of  the 
oxygen  in  the  CO2  recombines  with  the  fuel  forming  the  com- 
bustible gas — carbon  monoxide  (CO).  Because  of  the  dis- 
tilling effect  of  the  heat  in  the  bed,  the  volatile  hydrocarbons 
of  the  coal  are  set  free  and  mingle  with  the  CO  formed  by 
the  combustion.  The  producer  gas  consists,  therefore,  prin- 
cipally of  CO,  with  a  certain  proportion  of  the  volatile  hydro- 
carbons of  the  coal  such  as  marsh  gas,  ethylene,  and  some  oil 
vapor. 

Since  the  hydrocarbons  are  easily  condensed  on  coming  into 
contact  with  the  coal  walls  of  the  piping,  to  form  trouble  mak- 
ing tars  and  oils,  they  must  either  be  washed  out  of  the  gas 
in  the  purifier  or  passed  again  through  the  high  temperature 
zone  to  convert  them  into  permanent  gases.  In  the  usual  pro- 
ducer, the  hydrocarbons  are  reheated,  as  they  form  a  consider- 
able percentage  of  the  heat  value  of  the  gas.  After  the  volatile 
constituents  are  reheated,  the  gases  pass  through  the  boiler 
(B),  which  absorbs  the  heat  of  the  gas  in  generating  steam, 
and  from  this  point  the  gases  enter  the  scrubber  where  the  dust 
and  the  residual  tars  are  removed.  The  scrubber,  which  is  a 
sort  of  filter,  is  an  important  factor  in  the  generating  plant, 
for  if  the  dust  and  dirt  were  allowed  to  pass  into  the  cylinder 
of  the  engine  it  would  only  be  a  question  of  a  short  time  until 
the  valves  and  cylinder  would  be  ground  to  pieces. 

When  the  steam  from  the  boiler  is  allowed  to  flow  into  the 


FUELS 


49 


ash  pit  of  the  producer  and  up  through  the  incandescent  fuel, 
the  heat  separates  the  water  vapor  into  its  two  elements,  oxy- 
gen and  hydrogen.  The  oxygen  set  free  combines  with  the 
carbon  in  the  coal  forming  more  carbon  monoxide,  while  the 
hydrogen  which  is  unaffected  by  the  combustion  adds  to  the 
heat  value  of  the  gas.  The  last  additions  to  the  combustion 
dut  to  the  disassociation  of  the  steam  are  really  what  is  known 
as  "water  gas."  A  limited  amount  of  steam  may  be  admitted 


H- 


Fig.    F-6.     Diagram    of    Suction    Gas    Producer    Showing    the    Generator, 
Boiler    and    Washer. 

continuously  in  this  manner  without  lowering  the  temperature 
of  the  fuel  below  the  gasifying  point,  and  its  presence  is  bene- 
ficial for  it  not  only  provides  more  CO  and  hydrogen  but  pro- 
duces it  without  introducing  atmospheric  nitrogen.  The  steam 
is  also  a  great  aid  in  preventing  the  formation  of  clinkers  on 
the  grate  bars.  Since  the  air  used  in  burning  the  fuel  in  the 
first  reaction  contains  about  79  per  cent  of  nitrogen,  which^is 
an  inert  gas,  the  producer  gas  is  greatly  diluted  by  this  unavoid- 
able admixture,  which  accounts  for  its  low  calorific  value. 

While  the  air  required  for  the  combustion  of  the  fuel  is 
drawn  through  the  producer  by  the  suction  of  the  engine  in 
the  example  shown  (SUCTION  PRODUCER),  there  is  a  tvoe 


50  FUELS 

in  common  use  called  a  PRESSURE  PRODUCER  in  which  the 
air  is  supplied  under  pressure  to  the  ash  pit  by  a  small  blower, 
which  causes  a  continuous  flow  of  gas  above  atmospheric 
pressure. 

Gas  producers  are  divided  into  two  classes:  suction  producers 
and  pressure  producers.  The  suction  producer  presents  the 
following  advantages: 

1.  The  pipe  line  is  always  less  than  atmospheric  pressure, 
hence  no  leaks  of  gas  to  the  air  are  possible. 

2.  The  regulation  of  the  gas  supply  is  automatic. 

3.  No  gas  storage  tank  is  required. 

4.  The  production  of  gas  begins  and  stops  with  the  engine. 

5.  Uniform  quality  of  gas. 

The  suction  producer  is  limited  to  power  application  and 
cannot  be  used  where  the  gas  is  to  be  used  for  heating,  as 
in  furnaces,  ovens,  etc.,  or  where  the  engine  is  at  a  distance 
from  the  producer,  unless  pumped  to  its  destination. 

The  pressure  producer  does  not  yield  a  uniform  quality  of 
gas,  hence  requires  a  storage  tank  where  low  quality  gas  will 
blend  with  gas  of  higher  calorific  values  and  produce  a  gas  of 
fairly  uniform  quality. 

The  pressure  producer  is  adapted  to  the  use  of  all  grades  of 
fuels,  such  as  bituminous  coal  and  lignite. 

Anthracite  coal  contains  little  volatile  matter  and  is  an  ideal 
fuel  for  the  manufacture  of  producer  gas,  while  bituminous  coal 
with  its  high  percentage  of  volatile  matter  and  tar,  requires 
more  efficient  scrubbing,  as  these  substances  must  be  removed 
from  the  gas. 

On  starting  the  producer  shown  by  Fig.  6,  the  producer  is 
filled  with  the  proper  amount  of  kindling  and  coal,  and  a 
blast  of  air  is  sent  into  the  ash  pit  by  a  small  blower,  the 
products  of  combustion  being  sent  through  the  by-pass  stack 
(K)  until  the  escaping  gas  becomes  of  the  quality  required  for 
the  operation  of  the  engine.  The  by-pass  valve  is  now  closed, 
and  the  gas  is  forced  through  the  scrubber  to  the  engine  until 
the  entire  system  is  filled  with  gas.  When  good  gas  appears 
at  the  engine  test  cock  the  engine  is  started,  and  the  blower 
stopped,  the  gas  now  being  circulated  by  the  engine  piston. 
The  volume  of  gas  generated  by  the  producer  is  always  equal 
to  that  required  by  the  engine  so  that  no  gas  receiver  or 
reservoir  is  required.  Because  of  the  friction  of  the  gas  in 
passing  through  the  fuel,  scrubber  and  piping  its  pressure  at 
the  engine  is  always  considerably  below  that  of  the  atmosphere, 


FUELS'  51 

which  of  course  reduces  the  amount  of  charge  taken  into  the 
cylinder.  Because  of  the  weak  gas  and  the  low  pressure  in 
the  piping,  it  is  necessary  to  carry  a  much  higher  compression 
with  producer  gas  than  with  natural  or  illuminating  gas. 

The  efficiency  of  a  producer  is  from  75  to  85  per  cent,  that 
is,  the  producer  will  furnish  gas  that  has  a  calorific  value  of 
an  average  of  80  per  cent  of  the  calorific  value  of  the  fuel  from 
which  it  is  made,  the  remaining  15  to  20  per  cent  being  con- 
sumed in  performing  the  combustion.  This  is  far  above  the 
efficiency  of  the  furnace  in  a  steam  boiler,  as  an  almost  theo- 
retically exact  amount  of  air  can  be  supplied  in  the  producer 
to  effect  the  combustion,  while  in  the  boiler  furnace  about  ten 
times  the  theoretical  amount  is  passed  through  the  fuel  bed 
to  burn  it.  Heating  up  this  enormous  volume  of  air  to  the 
temperature  of  the  products  of  combustion  consumes  a  large 
amount  of  fuel  and  reduces  the  efficiency  of  the  furnace  con- 
siderably. Because  of  the  reduction  in  the  air  supply,  a  gas 
fired  furnace  is  always  more  efficient  than  one  fired  with  coal. 
Producer  gas  with  300,000  British  thermal  units  per  thousand 
cubic  feet,  and  oil  having  130,000  British  thermal  units  per  gal- 
lon will  result  in  1,000  cubic  feet  of  gas  being  equal  to  about 
2.20  gallons  of  fuel  oil. 

If  the  gas  is  to  be  used  for  heating  ovens  or  furnaces  in  con- 
nection with  the  generation  of  power,  the  character  of  the  fuel 
will  be  determined  to  a  great  extent  by  the  requirements  of  the 
ovens  and  by  the  type  of  producer  used,  as  each  fuel  will  give 
the  gas  certain  properties.  Thus  gas  used  for  firing  crockery 
will  not  be  suitable  for  use  in  open  hearth  steel  furnaces,  as  the 
impurities  in  the  various  fuels  may  have  an  injurious  effect  on 
the  manufactured  product.  The  cost  of  the  fuel,  cost  of  trans- 
portation, heat  value,  purity,  and  ease  of  handling  are  all 
factors  in  the  selection  of  a  fuel. 

The  size  and  condition  of  a  fuel  is  also  of  importance.  Ex- 
ceedingly large  lumps  and  fine  dust  are  both  objectionable. 

Wet  fuel  reduces  the  efficiency  of  the  producer,  as  the  water 
must  be  evaporated,  this  causing  a  serious  heat  loss. 

With  careful  attention  a  producer  gas  engine  will  develop 
a  horse-power  hour  on  from  1  to  1J4  pounds  of  anthracite  pea 
coal,  and  in  many  instances  the  consumption  has  been  less 
than  this  figure.  The  efficiency  in  dropping  from  full  load  to 
half  load  varies  by  little,  one  test  showing  a  consumption  of 
1.1  pounds  of  coal  per  horse-power  hour  at  full  load  and  1.6 
pounds  of  coal  at  half  load.  Producer  gas  power  is  nearly  as 


52  FUELS 

cheap  as  water  power,  in  fact  the  producer  gas  engine  has  dis- 
placed at  least  two  water  plants  to  the  writer's  knowledge. 
According  to  an  estimate  made  by  a  we«ll  known  authority, 
Mr.  Bingham,  it  is  possible  for  a  producer  gas  engine  to  gen- 
erate power  for  only  .1  of  one  cent  more  per  K.W.  hour  than 
it  is  generated  at  Niagara  Falls. 

According  to  the  United  States  Bureau  of  Mines, 

"The  tests  in  the  gas  producer  have  shown  that  many  fuels 
of  so  low  grade  as  to  be  practically  valueless  for  steaming  pur- 
poses, such  as  slack  coal,  bone  coal  and  lignite,  may  be  econom- 
ically converted  into  producer  gas  and  may  thus  generate  suffi- 
cient power  to  render  them  of  high  commercial  value. 

"It  is  estimated  that  on  an  average  each  coal  tested  in  the 
producer-gas  plant  developed  two  and  one-half  times  the 
power  that  it  would  develop  in  the  ordinary  steam-boiler  plant. 

"It  was  found  that  the  low-grade  lignite  of  North  Dakota 
developed  as  much  power  when  converted  into  producer  gas 
as  did  the  best  West  Virginia  bituminous  coals  burned  under 
the  steam  boiler. 

"Investigations  into  the  waste  of  coal  in  mining  have  shown 
that  it  probably  aggregates  250,000,000  to  300,000,000  tons  yearly, 
of  which  at  least  one-half  might  be  saved.  It  has  been  dem- 
onstrated that  the  low-grade  coals,  high  in  sulphur  and  ash, 
now  left  underground,  can  be  used  economically  in  the  gas  pro- 
ducer for  the  ultimate  production  of  power,  heat  and  light, 
and  should,  therefore,  be  mined  at  the  same  time  as  the  high- 
grade  coal.  , 

"As  a  smoke  preventer,  the  gas  producer  is  one  of  the  most 
efficient  devices  on  the  market,  and  furthermore,  it  reduces 
the  fuel  consumption  not  10  to  15  per  cent,  as  claimed  for  the 
ordinary  smoke  preventing  device  offered  for  use  in  steam 
plants,  but  50  to  60  per  cent. 

(13)  Producer  Gas  From  Peat. 

The  production  of  gas  from  peat  having  a  low  water  content 
(up  to  about  20  per  cent)  for  use  in  suction  gas  engines  has 
already  met  with  considerable  success  in  Germany,  but  for  a 
number  of  years  efforts  have  been  made  to  utilize  peat  with  a 
water  content  as  high  as  50  to  60  per  cent  and  thus  eliminate 
the  costly  process  of  drying  the  raw  material. 

Difficulties  have  been  encountered  in  preventing  a  loss  of 
heat  through  radiation  and  other  causes,  and  in  getting  rid 
of  the  dust  and  tar  vapors  carried  over  by  the  gases  to  the 


FUELS 


53 


engine;  but  great  strides  have  been  made  recently  in  over- 
coming these  obstacles.  Peat  with  a  water  content  up  to  60 
per  cent  has  been  found  to  be  a  suitable  fuel.  Owing  to  its 
great  porosity  and  low  specific  gravity  it  presents  a  large  com- 
bustion surface  in  the  generator,  so  that  the  oxygen  in  the 
air  used  as  a  draft  can  easily  unite  with  the  carbon  of  the 
peat. 

One  of  the  great  difficulties  is  to  eliminate  the  tar  vapors 
that  clog  up  many  of  the  working  parts  of  the  engine.  The 
passing  of  the  gas  through  the  wet  coke  washers  and  dry.  saw- 


Fig.    F-7.     German    Producer    for    Generating    Producer    Gas    from    Peat. 

dust  cleansers  does  not  appear  to  have  thoroughly  remedied 
the  evil.  Efforts  were  therefore  made  to  remove  the  tar-form- 
ing particles  of  the  gas  in  the  generator  itself  or  to  render  them 
harmless.  That  of  the  Aktien-Gesellschaft  Gorlitzer  Masch- 
inenbau  Ansalt  und  Eissengiesserei  of  Gorlitz,  was  displayed  at 
the  exposition  at  Posen  in  1911.  The  gas  from  the  generating 
plant  was  employed  in  a  gas  suction  engine  of  300  horse-power 
used  to  drive  a  dynamo  for  developing  the  electric  energy  for  the 
exposition.  The  fuel  used  was  peat  with  a  water  content  of  about 
40  per  cent.  The  efficiency  and  economy  results  obtained  were 
very  promising. 


54  .  FUELS 

The  advantages  claimed  for  the  Gorlitz  engine  are  that  the 
sulphurous  gases  and  those  containing  great  quantities  of  tar 
products  are  drawn  down  by  the  suction  of  the  engine  through 
burning  masses  of  peat  and  thus  rid  of  their  deleterious  con- 
stituents. The  air  for  the  combustion  purposes  is  well  heated 
before  entering  the  combustion  chamber,  thereby  producing 
economical  results.  It  is  claimed  also  that  the  gas  produced 
by  its  system  is  so  free  from  impurities  that  the  cleaning  and 
drying  apparatus  may  be  of  the  simplest  kind. 

In  Stahl  und  Eisen,  an  abstract  is  given  of  a  paper  by  Carl 
Heinz  describing  a  peat  gas  producer,  built  by  the  Goerlitzer 
Maschinenbauanstalt.  We  are  indebted  to  Metallurgical  and 
Chemical  Engineering  for  the  translation  of  this  paper: 

Air  and  fuel  enter  the  producer  at  the  top,  and  the  gas  exit 
is  in  the  center  of  the  bottom  so  that  the  air  is  forced  to  pass 
through  the  center  of  the  producer,  decomposing  the  volatile 
matter  into  gases  of  calorific  value.  The  moisture  which  is 
present  in  the  peat  fuel  in  considerable  quantities  must  be 
taken  into  consideration.  For  its  decomposition  which  passing 
through  the  hot-fire,  zone  only  a  certain  amount  of  heat  is 
available.  It  is,  therefore,  important  that  the  heat  from  the 
gasification  be  fully  utilized. 

There  are  two  kinds  of  heat  losses  in  a  gas  producer,  due 
to  radiation  and  to  the  sensible  heat  of  escaping  gases.  Both 
these  amounts  of  heat,  however,  are  utilized  according  to  the 
special  design  of  this  producer.  The  air  circulates  first  through 
the  lower  conduit  and  comes  so  in  contact  with  the  warm 
scrubber  water.  A  part  of  the  air  which  has  been  preheated 
is  carried  upwards  through  the  pipe  A  in  the  center  of  the 
producer  where  it  is  thoroughly  preheated  by  the  hot  gases 
and  enters  then  the  air  superheater  B  in  which  the  temperature 
rises  to  a  still  higher  degree. 

The  other  part  of  the  air  passes  through  the  feet  of  the 
producer  into  an  air  jacket  which  envelops  the  whole  shell  of 
the  producer  and  enters  finally  the  producer  by  the  reversing 
valve  C  on  top  of  the  producer.  In  this  way  the  outer  surface 
of  the  producer  is  maintained  at  a  temperature  hardly  higher 
than  that  of  the  surrounding  air.  The  escaping  gases  are  cooled 
down  so  far  that  the  gas  outlet  into  the  scrubber  may  be 
touched  by  hand.  All  ordinary  heat  losses  are  thus  made  use 
of  in  the  gasification  process. 

If  there  is  a  large  excess  of  moisture  in  peat,  the  process  is 
somewhat  modified  by  regulating  both  air  supplies  in  such  a 


FUELS  55 

way  that  the  gasification  in  the  upper  part  of  the  fuel-bed 
takes  place  in  two  directions,  one  downwards  and  the  other 
upwards. 

It  seems  that  a  content  of  80  per  cent  moisture  and  20  per 
cent  dry  fuel  in  the  peat  is  about  the  limit  permitting  evapora- 
tion of  the  water,  but  it  is,  of  course,  impossible  to  obtain  in 
this  case  a  gas  of  calorific  value. 

The  modification  of  the  process  for  very  wet  fuel  is  as 
follows: 

When  the  fire  on  top  of  the  fuel  bed  appears  to  disappear, 
the  heater  opens  the  stack  and  valve  D.  Valve  C  is  then  closed, 
to  prevent  air  from  entering  on  top.  The  preheated  air  en- 
ters by  D  causing  a  down  draft  combustion  due  to  the  suction 
of  the  gas  engine  and  an  upward  combustion  due  to  the  draft 
in  the  stack.  The  moisture  is  evaporated  and  escapes  through 
the  stack.  When  the  fire  has  burned  through  at  the  top,  the 
valve  is  switched  over.  The  bad  smelling  gases  rising  from 
the  scrubber  enter  the  producer  together  with  air  and  are  there 
consumed. 

In  commercial  use  at  the  exhibition  in  Posen  the  whole  plant 
worked  continuously  day  and  night  and  cleaning  of  the  gas  en- 
gines was  necessary  only  every  three  months.  Slagging  of 
ashes  is  done  during  the  operation  of  the  producer,  without  any 
nuisance  from  dust. 

The  highest  percentage  of  moisture  in  peat  gasified  was  50 
per  cent.  The  fuel  consumption  per  horse-power  hour  is  2.2  Ib. 
(1  kg.)  of  peat.  Careful  tests  made  by  Prof.  Baer,  of  Breslau, 
showed  that  with  a  cost  of  peat  of  $1  per  ton  the  kw-hour  at 
the  switchboard  costs  0.15  cent. 

(14)  Crude  Oil  Producers. 

The  development  of  the  crude  oil  gas  producer,  for  which 
there  is  great  demand,  in  oil  regions  remote  from  the  coal 
field,  has  been  exceedingly  slow  but  it  is  believed  that  definite 
progress  has  recently  been  made  along  this  line.  The  most 
recent  notes  on  this  subject  relate  to  the  Grine  oil  producer. 
In  this  type  steam  spray  is  used  for  atomizing  the  oil  which  is 
introduced  into  the  upper  part  of  the  generator  where  partial 
combustion  takes  place.  The  downdraft  principle  is  then  ap- 
plied and  the  hydrocarbon  broken  up  and  the  tar  fixed  by 
passing  through  a  bed  of  incandescent  coke.  Mr.  Grine  reports 
that  a  power  plant  using  one  of  these  producers  has  been  in 
operation  a  year  in  California.  With  crude  oil  as  a  fuel  costing 


56  FUELS 

95  cents  per  barrel,  or  2.3  cents  per  gallon,  the  plant  is  reported 
to  develop  the  same  amount  of  power  per  gallon  of  crude  as  is 
ordinarily  developed  by  the  standard  internal  combustion  en- 
gine operating  on  distillates  at  7  cents  per  gallon.  Including 
the  cost  of  fuel,  labor,  supplies,  interest,  depreciation  and 
taxes,  Mr.  Grine  states  the  cost  per  b.h.p.  hour  to  be  0.76  cents 
for  a  plant  of  100  h.p.  rating. 

(15)  Operation  of  Producers. 

A  good  producer  operator  is  simply  a  good  fireman,  he  must 
know  how  to  keep  a  uniform  bed  of  coal  and  how  to  draw  the 
fire.  While  there  are  many  thousands  of  men  running  pro- 
ducer plants  without  previous  mechanical  training,  there  are 
now  but  few  steam  engineers  running  steam  engines  of  the  same 
capacity  but  what  have  had  at  least  two  years'  training  and  suffi- 
cient mechanical  knowledge  to  pass  an  examination  and  obtain  a 
license.  While  a  considerable  amount  of  skill  is  necessary 
to  obtain  the  best  efficiency  from  a  producer,  it  is  a  knack  that 
is  easily  acquired  in  a  short  time  by  "sticking  around"  the 
plant.  Skill  in  operating  a  producer  consists  chiefly  in  keeping 
the  right  sort  of  a  fire  without  damage  to  the  lining  by  poking 
down  ashes  and  clinkers.  When  a  new  plant  is  installed,  the 
manufacturer  generally  sends  an  instructor  to  operate  the  plant 
for  a  short  time  so  that  with  a  few  days  running  in  his  hands 
any  man  with  ordinary  intelligence  can  overcome  the  difficulties 
which  arise  from  time  to  time. 

While  there  are  many  types  of  producers,  the  main  difference 
will  be  found  in  the  character  of  the  draft,  that  is  whether  it 
is  up,  down,  or  crossways.  Down  draft  producers  are  generally 
used  with  bituminous  coals,  as  the  tars  and  oils  that  emanate 
from  the  coal  are  drawn  through  the  fire  which  converts  them 
into  a  permanent  gas,  and  avoids  the  difficulty  of  removing 
great  quantities  of  the  tar  from  the  producer.  An  up  draft 
producer  will  not  do  this  as  the  gas  is  drawn  directly  into 
the  mains  without  coming  into  contact  with  the  fire.  This 
would  result  in  considerable  expense  due  to  the,  frequent 
cleaning.  Anthracite  coal  which  does  not  contain  much  tar 
can  be  used  successfully  in  an  up  draft  producer. 

A  compromise  between  the  up  draft  and  down  draft  producer 
is  had  in  the  DOUBLE  ZONE  producer,  which  "burns  the 
candle  at  both  ends"  as  it  were,  a  fire  being  at  both  the  top  and 
bottom  of  the  producer.  Nearly  any  class  of  fuel  may  be 
used  with  this  type. 


FUELS  57 

It  should  be  remembered  that  a  hot  fire  and  fuel  are  required 
for  the  manufacture  of  gas,  and  that  the  ash  pit  and  grate  must 
be  kept  clear  of  the  ashes  and  clinkers  that  not  only  reduce 
the  temperature  of  the  fire,  but  also  reduce  the  gas  available  at 
the  cylinder  by  increasing  the  friction.  Shaking  down  and 
cleaning  out  will  in 'nearly  every  instance  start  a  bucking  pro- 
ducer into  operation. 

When  operating  under  full  load  a  much  hotter  fire  is  re- 
quired than  when  operating  under  a  reduced  load,  or  the  pro- 
ducer will  not  furnish  the  necessary  gas.  According  to  the 
size  of  the  producer,  the  depth  of  the  incandescent  fuel  will 
run  from  30  inches  in  the  large  sizes  to  15  inches  in  the 
smaller.  After  being  charged  up,  suction  producers  will  con- 
tinue to  give  gas  in  sufficient  quantities  with  the  bed  at  half 
this  depth.  This  is  only  possible  with  a  hot  producer,  and 
when  no  fuel  is  being  fed,  as  the  feeding  of  a  cold  charge  will 
reduce  the  output.  A  steady  depth  of  fire  should  be  kept  to 
maintain  a  uniform  quality  of  gas. 

In  suction  producers  careful  watch  should  be  kept  for  leaks, 
as  the  gas  being  below  atmospheric  pressure  gives  no  outward 
signs  of  dilution.  If  water  seals  are  used  in  the  system  they 
should  be  given  careful  attention.  When  using  coals  that  are 
rich  in  tar  or  hydrocarbons,  or  with  fuels  that  have  much 
fine  dust,  considerable  trouble  is  had  with  some  types  of  pro- 
ducers due  to  "caking"  or  to  the  adhesion  of  the  coal  particles 
to  the  walls  of  the  producers  or  to  their  adhesion  to  one  another. 
In  the  latter  case  the  "stickiness"  of  the  fuel  prevent  the 
proper  feed.  This  difficulty  may  often  be  overcome  by  a 
change  in  the  rate  of  feeding  or  by  regulating  the  depth  of 
the  incandescent  bed. 

Porosity  of  the  fuel,  and  the  rate  at  which  the  air  is  sup- 
plied to  the  producer  determines  the  depth  of  the  incandescent 
bed.  Particular  care  should  be  taken  that  the  blast  or  draft 
occurs  evenly  over  the  fire  surface,  and  that  no  holes  occur 
in  the  fire  which  will  cause  more  rapid  combustion  in  one 
spot  than  in  another.  Neglect  of  this  precaution  not  only 
causes  a  waste  of  fuel  but  often  results  in  the  fuel  "arching" 
and  preventing  further  feed.  The  producer  should  be  so  pro- 
portioned that  at  full  load,  the  rate  of  combustion  does  not 
exceed  24  pounds  of  fuel  per  square  foot  of  producer  area 
per  hour. 

In  his  researches,  Professor  Bone  (Iron  and  Steel  Institute, 
May,  1907)  has  shown  that  up  to  0.32  Ibs.  of  steam  per  Ib.  of 


58  FUELS 

coal  can  be  completely  decomposed  in  a  producer,  but  that, 
from  0.45  Ibs.  to  0.55  Ibs.  should  be  used,  approximately  80% 
more. 

Now,  in  considering  the  question  of  the  proper  proportion 
of  steam  for  the  production  of  gas  for  power  purposes  we  must 
bear  in  mind  that  as  much  heat  as  possible  should  be  utilized 
in  the  producer  itself.  Some  manufacturers  of  plant  go  so 
far  as  to  state  that  as  much  as  1  Ib.  of  steam  per  Ib.  of  coal 
should  be  used,  but  we  are  safe  in  saying  that  0.5  Ib.  to  0.7  Ib. 
should  be  the  figure  for  a  power  plant.  The  common  practice 
is  to  use  a  blast  saturation  of  55%  whenever  the  clinkering  char- 
acter of  the  coal  renders  it  possible.  This  figure  corresponds 
to  about  .57  of  steam  per  Ib.  of  coal  gasified. 

It  is  of  the  utmost  importance  that  the  proportion  of  steam 
and  air  should  be  constant,  and  the  best  figure  being  de- 
termined, it  should  not  be  varied  to  any  degree.  It  is  equally 
important  that  the  fuel  depth  should  be  left  constant.  By  this 
I  mean  that  not  only  should  the  coal  in  the  producer  be  kept 
at  a  specific  level,  but  the  position  of  the  fire  on  the  ash  bed 
should  be  kept  as  near  as  possible  a  fixed  point.  Ashes  should 
be  drawn  at  regular  intervals,  or,  if  desired,  continuously  by 
mechanical  means. 

Further,  the  supply  of  air  and  steam  should  be  regularly 
distributed,  so  that  the  velocity  of  the  gases  through  the  fuel 
shall  be  as  nearly  as  possible  regular  across  its  whole  area. 

In  some  cases  the  by-products  of  a  producer,  such  as  am- 
monia, tar,  etc.,  have  a  commercial  value,  and  if  a  large  amount 
of  gas  is  generated  it  will  sometimes  pay  to  select  a  fuel  that  is 
rich  in  these  particular  substances. 

(16)  Coal. 

Coal  which  is  the  basis  of  producer  gas,  is  composed  gen- 
erally speaking  of  the  combustible  matter,  moisture,  ash  and 
sulphur.  The  combustible  element  may  be  subdivided  into  the 
HYDROCARBONS,  OR  VOLATILES,  and  the  solid  fixed  car- 
bon. The  exact  composition  of  coal  is  generally  given  by  what 
is  known  as  PROXIMATE  analysis,  which  analysis  divides  the 
constituents  of  the  coal  into  five  groups,  viz.:  MOISTURE, 
VOLATILES,  FIXED  CARBON,  ASH,  and  SULPHUR. 
Ultimate  analysis  resolves  the  coal  into  its  ultimate  chemical 
elements,  such  as  hydrogen,  carbon,  nitrogen,  sulphur,  etc.,  and 
being  a  difficult  and  tedious  process  it  is  not  much  used. 


FUELS 


59 


The  proximate  analysis  gives  all  the  necessary  information 
and  takes  less  time  to  perform. 

The  CALORIFIC  VALUE  of  a  fuel  may  be  calculated  from 
its  analysis,  or  may  be  determined  by  means  of  the  CALORI- 

VALUES  OF  COAL 


Location 
of 
Mine 

PROXIMATE    ANALYSIS 

Calorific 
Value  in 
B.  T.  U. 
per  Lb. 
of  Coal 

Moisture 

Volatile 
Matter 

Fixed 
Carbon 

Ash 

Sulphur 

ANTHRACITE 

Moitliern  Pa. 

3-39 

4.41 

83-30 

8.17 

•73 

13,200 

Eastern  Pa. 

}37° 

3-°7 

86.42 

6.18 

•63 

13.440 

Western  Pa. 

3-12 

3-76 

81.60 

10.61 

•53 

12,875 

SEMI- 
ANTHRACITE 

1.25 

8.15 

83-30 

627 

1.63 

13,900 

SEMI- 
BITUMINOUS 

Pennsylvania 

.80 

15.60 

77.40 

5-35 

•85 

14.900 

Pennsylvania 

i-55 

i6-45 

71-50 

8.63 

1.87 

14,200 

Pocahontai 
Va. 

1.  00 

21.00 

24.40 

3-02 

-58 

15,100 

West 
Virginia 

.9° 

17-83 

77.70 

3-30 

.27 

15.230 

BITUMINOUS 

Youghiogheny 
Pa. 

I.OO 

36-5o 

59.00 

2-59 

.86 

14.400 

Sample  No.  2          " 

1.2O 

30.18 

59.00 

8.84 

.78 

14,000 

Hocking 
Valley 

6-5 

35-o6 

48.80 

8.05 

i-59 

12.100 

Kentucky 

4.00 

34-0° 

54-70 

7.00 

•03 

I2,800 

Indiana 

8.00 

30.20 

54  20 

7.60 

I2,5OO 

Illinois 

10.50 

36  15 

37.00 

12.90 

3-45 

10,500 

Colorado 

6.00 

38.01 

47.90 

8.09 

12,200 

LIGNITE 

9.00 

42  26 

44-30 

3-27 

1.18 

11,000 

60  FUELS 

METER  from  a  sample  of  the  coal;  the  latter  method  is  the 
most  reliable.  Table  gives  approximately  the  calorific  values, 
and  the  proximate  analysis  of  several  representative  coals  from 
various  sections  of  the  country.  The  values  given  in  the  table 
are  not  exact,  as  the  coal  from  each  locality  varies  considerably 
in  quality,  but  the  figures  will  indicate  what  may  be  expected 
from  .each  type  of  coal. 

Connellsville,  Pa.,  Coke  has  a  calorific  value  of  approximately 
13,000  B.T.U.S.  per  pound,  contains  no  volatile  matter,  and  has 
an  approximate  content  of  10%  ash.  Coke  is  a  valuable  fuel 
for  the  gas  producer,  but  is  rather  expensive.  It  is  clean  and 
the  absence  of  volatile  matter  reduces  the  "scrubbing"  problem 
to  a  minimum. 

Small  coal  such  as  buckwheat  and  pea  contain  a  much  higher 
percentage  of  moisture  than  given  in  the  table,  running  from 
5%  to  10%  higher  than  the  given  values. 

Bituminous  coal  is  high  in  hydrocarbons  or  volatiles  which 
condense  easily  and  form  tar.  If  the  tar  is  not  removed  or 
converted  into  a  permanent  gas,  it  will  clog  the  passages  of  the 
producer  and  the  engine  and  cause  trouble. 

The  removal  of  the  tar  and  ash  from  a  gas  is  called  SCRUB- 
BING, and  is  performed  by  a  device  much  resembling  a  filter. 
Anthracite  coal  and  coke  are  low  in  volatiles  or  hydrocarbons, 
and  therefore  do  not  cause  trouble  with  tar  deposits. 

A  high  percentage  of  volatile  matter  also  causes  trouble  by 
the  tar  cementing  the  particles  of  fuel  together.  This  inter- 
feres with  the  proper  action  of  the  producer. 

Fuels  having  a  high  percentage  of  ash  call  for  perfect  filter- 
ing or  "scrubbing"  as  such  fuels  will  fill  the  gas  passages  with 
dust  Dust  should  be  kept  out  of  the  engine  at  all  costs,  for 
the  dust  even  in  a  quantity  will  cause  wear  in  the  cylinder. 

Depending  on  the  quality  of  the  fuel,  bituminous  coal  will 
produce  about  4*/2  pounds  of  ammonia  and  12  gallons  of  tar 
with  about  5%  of  sulphur. 

Anthracite  coal  will  produce  approximately  six  pounds  of 
tar,  and  two  pounds  of  ammonia  with  traces  of  sulphur. 

Loose  Anthracite  coal  requires  approximately  40  cubic  feet 
of  storage  space  per  ton  of  2240  pounds  and  weighs  about  56 
pounds  per  cubic  foot  (market  sizes). 

Loose  Bituminous  coal  requires  approximately  45  cubic  feet 
of  storage  space  per  ton  of  2240  pounds,  and  weighs  about  52 
pounds  per  cubic  foot  in  market  sizes. 

Dry   coke    requires    approximately   85    cubic    feet    of   storage 


FUELS  61 

space  per  ton  of  2240  pounds,  and  weighs  about  26  pounds  per 
cubic   foot. 

(17)  Fuel  Oils. 

Crude  oil,  a  natural  product,  is  the  base  of  the  fuels  most 
commonly  used  in  internal  combustion  engines,  especially  in 
the  smaller  sizes.  From  this  compound  the  following  deriva- 
tives are  obtained  by  the  process  of  distillation,  a  separation 
possible  because  of  the  different  boiling  points  of  the  various 
oils.  As  each  derivative  or  DISTILLATE  has  a  different  boiling 
point,  the  temperature  of  the  crude  oil  is  maintained  at  the 
boiling  point  of  that  product  that  is  desired,  and  the  resulting 
vapor  is  condensed.  The  following  list  is  not  anywhere  near 
complete  for  there  are  several  hundred  distinctly  different  dis- 
tillates, but  it  contains  those  that  are  of  the  most  interest  to 
the  engine  man. 

1.  Crude    Oil. 

2.  Gasoline. 

3.  Naptha. 

4.  Solar  Oil. 

5.  Kerosene. 

The  specific  gravity  of  the  crude  oil  as  obtained  in  the  field 
will  range  from  12°  to  56°  Beaume  scale.  The  crude  from 
Pennsylvania  will  average  40°  Beaume  while  that  from  Texas 
will  average  20?.  The  accompanying  table  will  give  the  calo- 
rific values  and  general  properties  of  the  principle  liquid  fuels. 
It  should  be  noted  that  the  weight  or  density  of  the  liquids  is 
given  in  terms  of  specific  gravity  or  Beaume  scale,  in  which  the 
SPECIFIC  GRAVITY  of  the  fuel  is  the  ratio  of  its  weight  per 
unit  volume  to  the  weight  of  an  equivalent  volume  of  water.  •  The 
specific  gravity  of  a  liquid  is  generally  determined  by  an  in- 
strument known  as  a  HYDROMETER  which  consists  of  a  glass 
tube  sealed  at  both  ends  carrying  a  graduated  scale  on  the 
upper  portion  of  the  stem,  and  a  ballast  weight  of  shot  or 
mercury  at  the  bottom. 

The  hydrometer  is  floated  in  the  liquid  to  be  tested,  and  the 
lower  the  specific  gravity,  the  lower  the  hydrometer  sinks, 
and  vice  versa.  The  specific  gravity  of  the  liquid  is  read 
directly  from  the  graduation  on  the  stem  that  are  on  a  level 
with  the  .surface  of  the  liquid  under  test.  As  in  the  case  of 
thermometers,  hydrometers  are  all  graduated  in  two  different 
scales,  the  specific  gravity  scale  and  the  Beaume  scale.  The  spe- 


62 


FUELS 


cific  gravity  scale  reads  at  1.00  when  floated  on  distilled  water, 
and  the  Beaume  at  10.00  when  floated  on  the  same  liquid. 

A  difference  in  temperature  affects  the  density  of  a  liquid, 
hence  all  hydrometers  are  graduated  for  a  standard  temperature 
of  60°F  unless  otherwise  specified.  For  a  difference  of  10°F 
there  is  a  variation  of  one  degree  gravity  in  the  Beaume  scale, 
and  for  a  difference  of  20°F  in  temperature  there  is  a  change 
of  one  degree  on  the  specific  gravity  scale.  If  the  temperature 
differs  from  60°F,  the  corresponding  correction  should  be  made 
in  the  reading. 

To  convert  the  Beaume  reading  (B)  to  terms  of  the  specific 
gravity  scale  (S)  use  the  following  formula: 
140 

S  = =•  specific  gravity. 

130 +  B 
140 

B  = —  Beaume  scale. 

S 

Properties  of  Oils 

Degrees     Specific   Weight  B.  T.  U.'S  B.  T.  U.'S 
Baume 

Gasoline   67.2 

Heavy  naphtha    64.6 

Kerosene    48.8 

W.  Virginia  crude    40.0 

Penn.  fuel  oil  31.9 

Kansas  crude   29.0 

Fuel   oil    22.7 

California  crude    22.5 

California  crude    15.2 

Alcohol,  95% 41.9 

It  will  be  noted  that  the  petroleum  products  contain  an  enor- 
mous amount  of  heat  energy,  nearly  25%  more  than  that  of  the 
same  weight  of  pure  carbon.  It  will  also  be  noted  that  the 
lighter  products  such  as  gasoline,  kerosene,  etc.,  have  more  heat 
per  pound  but  less  per  gallon  than  the  heavier  oils.  This  is  rather 
confusing  at  first,  but  as  will  be  seen  after  deliberation  that 
the  heavier  fuel  is  the  most  economical  since  the  least  is  used 
per  horse-power,  and  is  bought  by  the  gallon.  The  calorific 
values  given  in  the  table  are  obtained  by  a  colorimeter,  and  are 
burnt  in  the  open  air,  and  consequently  have  a  different  heating 
value  when  under  compression  in  the  cylinder  of  the  engine. 


Gravity 

.7125 
.7216 
.7848 
.8251 
.8660 
.8816 
.9176 
.9248 
.9646 
.816 

per  gal. 
5.932 

6.011 
6.538 
6.874 
7.215 
7.345 
7.645 
7.710 
8.036 
6.798 

per  Ib. 

21120 
20527 
20018 
19766 
19656 
19435 
19103 
18779 
18589 
10500 

per  gal. 
125,284 

123,388 
130,877 
135,871 
141,818 
142,750 
146,042 
144,786 
149,381 
71,380 

FUELS  63 

In  all  cases  the  liquids  are  vaporized  before  being  introduced 
in  the  cylinder,  the  more  volatile  liquids  such  as  gasoline  being 
converted  into  vapor  at  atmospheric  temperature,  and  the 
heavier  non-volatiles  by  being  sprayed  into  a  heated  vessel  or 
preheated  air.  The  percentage  of  liquid  fuel  contained  in  a  cubic 
foot  of  air  vapor  mixture  depends  on  the  temperature,  the  boil- 
ing point  of  the  liquid  and  upon  the  pressure  and  humidity. 

Gasoline  consists  principally  of  compounds  of  the  methane 
series,  the  one  representative  of  gasoline  being  Hexane  (C6Hi4). 
It  requires  15.5  pounds  of  air  for  combustion  theoretically  and 
about  10  per  cent  more  in  practice.  The  formation  of  gasoline 
vapor  produces  a  drop  in  temperature  of  50°F,  and  should  be 
heated  100°F  above  the  atmosphere  for  the  best  results.  The 
volume  of  air  required  for  the  combustion  is  about  192  cubic 
feet.  With  alcohol  at  20  cents  per  gallon  and  gasoline  at  \2l/2 
cents  the  number  of  B.T.U.'s  for  one  cent  in  the  case  of  alcohol 
is  3594  and  9265  in  the  case  of  gasoline.  In  the  engine  the 
difference  is  not  so  great  owing  to  the  difference  in  compression 
pressures. 

(18)  Tar  for  Fuel. 

Because  of  the  increasing  interest  in  the  Diesel  type  engine 
and  the  low  grade  fuels  that  it  has  made  possible,  we  quote 
the  specifications  laid  down  by  Dr.  Rudolph  Diesel,  the  in- 
ventor, before  the  English  Institution  of  Engineers. 

(1.)  Tar-oils  should  not  contain  more  than  a  trace  of  consti- 
tuents insoluble  in  xylol.  The  test  on  this  is  performed  as 
follows: — 25  grammes  (0.88  oz.  av.)  of  oil  are  mixed  with  25 
cm.3  (1.525  cub.  in.)  of  xylol,  shaken  and  filtered.  The  filter- 
paper  before  being  used  is  dried  and  weighed,  and  after  filtra- 
tion has  taken  place  it  is  thoroughly  washed  with  hot  xylol. 
After  re-drying  the  weight  should  not  be  increased  by  more 
than  0.1  gr. 

(2.)  The  water  contents  should  not  exceed  1  per  cent.  -The 
testing  of  the  water  contents  is  made  by  the  well-known  xylol 
method. 

(3.)     The  residue  of  the  coke  should  not  exceed  3  per  cent. 

(4.)  When  performing  the  boiling  analysis,  at  least  60  per 
cent  by  volume  of  the  oil  should  be  distilled  on  heating  up  ta 
300°  C.  The  boiling  and  analysis  should  be  carried  out  accord- 
ing to  the  rules  laid  down  by  the  Trust.  (German  Tar  Produc- 
tion Trust  on  Essen-Ruhr.) 

(5.)     The    minimum    calorific   power    must    not    be    less    than 


64  FUELS 

8,800  cal.  per  kg.  For  oils  of  less  calorific  power  the  purchaser 
has  the  right  of  deducting  2  per  cent  of  the  net  price  of  the 
delivered  oil,  for  each  100  cal.  below  this  minimum. 

(6.)  The  flash-point,  as  determined  in  an  open  crucible  by 
Von  Holde's  method  for  lubricating  oils,  must  not  be  below 
65°  C. 

(7.)  The  oil  must  be  quite  fluid  at  15°  C.  The  purchaser  has 
not  the  right  to  reject  oils  on  the  ground  that  emulsions  appear 
after  five  minutes'  stirring  when  the  oil  is  cooled  to  8°. 

Purchasers  should  be  urged  to  fit  their  oil-storing  tanks  and 
oil-pipes  with  warming  arrangements  to  redissolve  emulsions 
by  the  temperature  falling  below  15°  C. 

(8.)  If  emulsions  have  been  caused  by  the  cooling  of  the 
oils  in  the  tank  during  transport,  the  purchaser  must  redissolve 
them  by  means  of  this  apparatus. 

Insoluble  residues  may  be  deducted  from  the  weight  of  oil 
supplied. 

Coal  tar  oil  is  the  distillate  of  the  tar  obtained  from  gas 
works,  from  which  all  valuable  commercial  materials  such  as 
aniline  have  been  removed.  Coal  oil  tar  is  also  known  as 
creosote  oil  and  anthracene  oil,  the  heat  value  of  which  is  not 
quite  16,000  B.T.U.  per  pound. 

(19)  Residual  Oils. 

Residual  oil  is  the  residue  left  after  the  lighter  oils  have  been 
distilled  from  the  petroleum,  which  before  the  advent  of  the 
Diesel  engine  were  useless.  Residual  oil  which  was  hardly 
fluid  at  ordinary  temperatures  has  been  successfully  used  in  the 
Diesel  and  semi-Diesel  types  of  engines,  by  preheating  it  be- 
fore admission  to  the  inlet  valves.  The  enormously  increased 
demand  for  gasoline  has  resulted  in  a  great  increase  of  the 
formerly  useless  residual  oil  so  that  it  is  possible  that  the  de- 
mand for  gasoline  will  make  the  production  of  the  residual  great 
enough  so  that  it  can  be  seriously  considered  as  a  fuel- 

(20)  Gasoline. 

Gasoline  is  by  the  far  the  most  widely  used  fuel  for  internal 
combustion  engines  because  of  its  great  volatility  and  the  ease 
with  which  it  forms  inflammable  mixtures  with  the  air  at  ordi- 
nary temperatures.  Another  point  in  its  favor  is  the  fact  that 
it  burns  with  a  minimum  of  sooty  or  tarry  deposits,  without 
a  disagreeable  smell  with  moderate  compression  pressures  and 
without  preheating  through  a  v/ide  range  of  air  ratios.  Gasoline 


FUELS  65 

is  a  product  of  crude  oil  from  which  it  is  obtained  by  a  process 
of  distillation,  and  as  it  forms  but  a  small  percentage  of  the 
crude  oil  it  is  rapidly  becoming  more  and  more  expensive  as 
the  demand  increases.  Some  Pennsylvania  crude  oils  will  yield 
as  much  as  20  per  cent  of  their  weight  in  gasoline,  while  the  low 
grade  Texas  and  California  crudes  very  seldom  contain  more 
than  3  per  cent. 

When  considered  as  a  term  applying  to  some  specific  product, 
the  word  "Gasoline"  is  a  very  flexible  expression  as  it  covers  a 
wide  range  of  specific  gravities,  boiling  points,  and  composi- 
tions, the  latter  items  depending  on  the  demand  for  the  fuel 
and  the  taste  of  the  manufacturer.  Since  the  specific  gravity 
of  gasoline  is  a  factor  that  determines  its  suitability  for  the 
engine,  at  least  in  regard  to  its  evaporating  power  or  volatility, 
it  is  graded  according  to  its  density  in  Beaume  degrees  as  de- 
termined by  the  hydrometer.  According  to  this  scale  gasoline 
will  range  from  85°  to  60°  Beaume,  and  even  lower,  although 
60°  is  supposed  to  mark  the  lowest  limit  and  to  form  the  dividing 
line  between  gasoline  and  naphtha. 

The  density  of  the  gasoline  in  Beaume  degrees  is  an  index 
to  the  volatility,  for  the  higher  the  degree  as  indicated  on  the 
hydrometer,  the  higher  is  the  volatility  at  a  given  temperature, 
consequently  a  high  degree  gasoline  will  give  a  better  mixture 
at  a  low  temperature  than  one  of  a  low  degree.  In  cold  weather 
all  gasoline  should  be  tested  with  a  hydrometer  when  pur- 
chased to  insure  a  grade  that  will  be  volatile  enough  for  easy 
starting  when  the  engine  is  cold.  In  cold  weather  the  gasoline 
should  not  be  lower  than  68°,  and  for  the  best  results  should 
be  above  72°,  at  least  for  starting  the  engine.  Good  gasoline 
should  evaporate  rapidly  and  should  produce  quite  a  degree  of 
cold  when  a  small  amount  is  spread  on  the  palm  of  the  hand, 
and  it  should  leave  neither  a  greasy  feeling  nor  a  disagreeable 
odor  after  its  evaporation. 

The  high  gravity  gasoline  is  of  course  the  most  expensive, 
as  there  is  less  of  it  in  a  gallon  of  the  crude  oil  from  which  it  is 
made;  gasoline  of  76°  Beaume  being  approximately  15c.  per  gal- 
lon in  carload  lots,  while  naphtha  of  58°  Beaume  brings  8^c. 
per  gallon. 

The  calorific  value  of  gasoline  increases  as  the  gravity  Beaume 
decreases  per  gallon;  85°  gasoline  having  approximately  113,000 
B.  T.  U.  per  gallon  while  58°  naphtha  has  an  approximate  value 
of  122,000  B.T.U.  per  gallon.  The  calorific  value  remains  nearly 
constant  per  pound  for  all  gravities. 


66  FUELS 

It  should  be  remembered  that  heat  is  absorbed  in  evaporating 
gasoline  as  well  as  in  evaporating  water,  and  that  effects  of 
cold  weather  are  greatly  increased  by  the  amount  of  heat  ab- 
sorbed, (or  cold  produced)  by  the  vaporization  of  the  fuel. 
While  the  heat  absorbed  by  evaporating  a  given  quantity  of 
gasoline  is  only  .45  per  cent  of  that  absorbed  by  an  equal  amount 
of  water,  it  is  a  fact  that  this  heat  must  be  supplied  from  some 
source  to  prevent  a  reduction  in  the  vapor  density.  In  starting 
the  engine,  the  heat  of  evaporation  is  supplied  by  the  atmosphere* 
and  should  the  temperature  of  the  air  be  below  that  required 
for  a  given  vapor  density,  the  engine  will  refuse  to  start. 

By  the  use  of  two  tanks  and  a  three  way  valve,  it  is  possible 
to  use  two  grades  of  fuel:  one  tank  containing  high  gravity 
gasoline,  and  the  other  low  gravity;  the  high  gravity  being  used 
for  starting  the  engine  in  cold  weather,  and  the  cheaper,  low 
gravity,  being  used  for  continuous  running  after  the  engine  is 
warmed  up — the  change  of  fuels  being  made  by  throwing  over 
the  three  way  valve. 

The  VAPOR  DENSITY  of  gasoline  vapor  is  the  ratio  of  the 
weight  of  the  vapor  compared  with  the  weight  of  an  equal  vol- 
ume of  dry  air  at  the  same  temperature.  If  the  weight  of  a  cubic 
foot  of  gasoline  vapor  is  divided  by  the  weight  of  a  cubic  foot  of 
air  the  same  temperature  the  result  will  be  the  vapor  density  of 
the  gasoline  vapor.  Compared  to  air,  the  gasoline  vapor  is 
quite  heavy  so  that  if  a  small  quantity'  of  gasoline  is  poured 
on  the  top  of  a  table,  the  vapor  will  flow  over  the  edge  of  the 
table  and  drop  to  the  floor  where  it  will  remain  until  it  has 
united  with  the  air  by  the  process  of  diffusion.  Experiments 
have  shown  that  pure,  dry  gasoline  vapor  has  a  density  of 
about  3.28,  or  in  other  words  weighs  3.28  times  as  much  as  an 
equal  volume  of  dry  air.  This  weight  of  course  is  the  weight  of 
pure  vapor  which  is  considerably  heavier  than  the  mixture  of 
vapor  and  air  that  is  used  in  the  cylinder  of  the  engine. 

Dampness,  or  the  presence  of  water  vapor  in  the  air  reduces 
the  quantity  of  gasoline  vapor  taken  up  by  the  air,  but  only  by  a 
small  amount,  the  maximum  difference  being  only  about  2  per 
cent.  Since  it  is  very  likely  that  the  water  vapor  is  broken  up 
into  its  original  elements,  oxygen  and  hydrogen,  by  the  heat  of 
the  combustion  it  is  likely  that  there  is  no  heat  loss  due  to  the 
vapor  passing  out  through  the  exhaust.  The  principal  trouble 
due  to  dampness  is  the  mixture  of  water  and  liquid  gasoline 
caused  by  the  condensation  of  the  water  vapor. 

All   gasolines  and  oils  contain  water  to  a  more   or  less  de- 


FUELS  67 

gree,  hence  provision  should  be  made  for  the  draining  of  the 
water  which  collects  in  the  bottom  of  the  tank.  Water  in  liquid 
fuels  is  the  cause  of  much  trouble. 

Water  in  gasoline  may  be  detected  by  dropping  scrapings 
from  an  indelible  pencil  into  a  sample  of  the  suspected  fluid.  If 
water  is  present  in  any  quantity  the  gasoline  will  assume  a 
violet  color. 

In  filling  a  supply  tank  with  gasoline,  a  chamois  filter  or 
chamois  lined  funnel  should  always  be  used,  as  the  chamois 
skin  allows  the  gasoline  to  pass  but  retains  the  water  and  im- 
purities contained  therein.  There  are  many  funnels  of  this  type 
now  on  the  market. 

The  rate  at  which  gasoline  burns  depends  on  the  amount  of 
surface  presented  to  the  air  by  the  fluid,  for  a  given  quantity  of 
gasoline  burns  faster  in  a  wide  shallow  vessel  than  in  a  deep  jar. 
Since  a  spray  of  minute  particles  presents  an  enormously  greater 
surface  than  the  liquid-  its  burning  speed  is  correspondingly 
greater,  and  as  a  true  vapor  has  an  almost  limitless  area,  its 
speed  is  much  greater  than  that  of  the  spray,  the  combustion 
under  the  latter  condition  being  almost  instantaneous.  Besides 
the  question  of  subdivision  of  the  liquid,  the  rate  of  combustion 
also  depends  on  the  intimacy  of  contact  of  the  vapor  with  the 
air  and  on  the  pressure  applied  to  the  vapor  as  previously  ex- 
plained under  the  head  of  "COMPRESSION"  in  another  chapter. 

CARBURETING  AIR,  or  producing  an  explosive  mixture  of 
gasoline  vapor  and  air  is  accomplished  by  two  different  methods, 
first  by  passing  the  air  over  the  surface  of  the  liquid,  or  by  pass- 
ing it  through  the  liquid  in  bubbles;  second  by  spraying  the 
liquid  into  the  air.  The  latter  is  the  method  most  generally  in  use 
at  the  present  time,  the  spray  being  formed  by  the  suction  of  the 
intake  air  upon  the  open  end  of  the  spray  nozzle.  The  vapor 
density  of  the  mixture  thus  formed  depends  on  the  suction  of 
the  air  and  upon  the  nozzle  opening,  either  of  which  may  be 
varied  in  the  modern  carburetor  to  vary  the  richness  of  the 
mixture. 

As  a  suggestion  to  the  users  of  gasoline  we  append  the 
following  remarks. 

Gasoline  vapor  will  readily  combine  with  air  to  form  ex- 
plosive mixtures,  at  ordinary  temperature.  This  property  at 
once  makes  it  the  most  suitable  fuel  and  the  most  dangerous 
to  handle. 

Never  fill  tanks  or  expose  gasoline  to  the  air  in  the  presence 
of  an  open  flame,  or  do  not  attempt  to  determine  the  amount 


68  FUELS      - 

of  gasoline  in  a  tank  with  the  aid  of  a  match.  There  are  a 
number  of  people  who  have  successfully  accomplished  this  feat, 
and  a  very  great  number  who  have  not. 

Be  very  sparing  in  the  use  of  matches  around  a  gasoline 
engine;  there  are  such  things  a§  leaks. 

Always  carefully  replace  the  stopper  or  filler  cap  in  a  gaso- 
line tank  after  filling.  Never  use  the  same  funnel  for  water 
and  gasoline,  and  avoid  any  possibility  of  water  finding  its  way 
into  the  tank. 

If  you  do  succeed  in  igniting  a  quantity  of  free  gasoline,  do 
not  attempt  to  extinguish  the  fire  with  water.  Pouring  water  on 
burning  gasoline  spreads  the  fire.  Extinguish  it  with  earth  or 
sand,  or  by  the  use  of  one  of  the  dry  powder  extinguishers  now 
on  the  market. 

Water  may  be  removed  from  gasoline  by  placing  a  few  lumps 
of  dessicated  calcium  chloride  in  the  tank,  the  amount  depend- 
ing on  the  quantity  of  water. 

Calcium  chloride,  has  a  great  capacity  for  absorbing  water, 
and  in  a  short  space  of  time  will  absorb  all  of  the  moisture 
contained  in  the  tank. 

The  best  way  to  introduce  the  chloride  is  to  wrap  the  lumps 
in  a  sheet  of  wire  gauze  and  lower  into  tank  with  a  wire,  the 
wire  allowing  it  to  be  easily  removed  when  saturated  with  water. 

(21)  Benzol. 

Benzol  has  been  used  to  some  extent  in  Europe  as  a  fuel, 
its  use  being  due  to  the  rapidly  increasing  cost  of  gasoline. 

Benzol  is  a  distillate  of  coal  tar,  and  is  a  by-product  of  the 
coke  industry.  In  England  benzol  brings  approximately  the 
same  price  as  gasoline  (called  petrol),  but  benzol  proves  eco- 
nomical for  the  reason  that  it  develops  more  power  per  gallon. 

Benzol  is  not  as  volatile  as  gasoline,  but  is  sufficiently  volatile 
to  allow  of  easy  motor  starting. 

Benzol  is  also  used  for  denaturing  alcohol. 

(22)  Alcohol. 

Alcohol  is  of  vegetable  origin,  being  the  result  of  the  de- 
structive distillation  of  various  kinds  of  starchy  plants  or  vege- 
tables. Starch  is  the  base  of  alcohol. 

'  As  a  fuel,  alcohol  has  much  in  its  favor,  as  it  causes  no  carbon 
deposit,  has  smokeless  and  odorless  exhaust,  can  stand  high 
compression,  and  requires  less  cooling  water  than  gasoline,  as 


FUELS  69 

the  heat  loss  is  less  through  the  cylinder  walls,  and  for  this 
reason  it  is  more  efficient  fuel  than  gasoline. 

At  the  present  time  the  price  of  alcohol  prohibits  its  general 
use.  In  order  that  alcohol  equal  gasoline  in  price  per  horse 
power  hour,  it  should  sell  for  lOc.  per  gallon,  the  price  of 
gasoline  being  15c.  per  gallon. 

Alcohol  can  be  used  in  any  ordinary  gasoline  engine  with 
readjustment  of  carburetor  and  the  compression. 

The  nozzle  in  the  carburetor  has  to  be  of  larger  bore  for  alco- 
hol than  for  gasoline,  and  the  compression  for  alcohol  than  for 
in  the  neighborhood  of  180  pounds  per  square  inch. 

The  inlet  air  should  be  heated  to  about  280°F  for  alcohol 
fuel;  approximately  6%  of  the  heat  of  the  alcohol  is  required 
for  its  vaporization.  Alcohol  is  much  safer  to  handle  than 
gasoline  owing  to  its  low  volatility. 

90%  alcohol  has  a  calorific  value  of  10,100  B.T.U.  per  pound, 
its  specific  gravity  being  .815. 

WOOD,  or  METHYL  alcohol  is  made  by  distilling  the  starch 
contained  in  the  fibres  of  some  species  of  wood  (Poisonous). 

GRAIN,  or  ETHYL  alcohol  is  the  result  of  the  distillation  of 
the  starch  contained  in  grains,  potatoes,  molasses,  etc.  ETHYL, 
or  GRAIN  alcohol  rendered  unfit  for  drinking  by  the  addition 
of  certain  substances,  is  called  DENATURED  ALCOHOL. 
The  process  of  denaturing  does  not  affect  the  calorific  value  of 
alcohol  to  any  extent. 

(23)  Kerosene  Oil. 

Kerosene  is  a  fractional  distillate  of  crude  oil  which  has  a 
considerably  higher  vaporizing  temperature  than  gasoline.  It 
does  not  form  an  inflammable  mixture  with  the  air  at  ordinary 
temperatures,  but  is  vaporized  in  practice  by  spraying  it  into  a 
chamber  heated  to  above  200°F.  Kerosene  forms  a  greater  per- 
centage of  crude  oil  than  gasoline  and  as  there  has  been  less 
demand  for  it  up  to  the  present  time  it  is  much  cheaper.  Penn- 
sylvania crude  oil  produces  only  20  per  cent  of  gasoline  while 
the  kerosene  contents  will  average  nearly  42  per  cent  accord- 
ing to  figures  at  hand. 

Kerosene  has  a  very  high  calorific  value  per  gallon,  8.5  gal- 
lons of  kerosene  having  the  same  heating  effect  as  10  gallons 
of  gasoline.  Because  of  its  high  calorific  value  and  its  low  cost 
per  gallon,  many  types  of  engines  have  been  developed  for  its 
use  during  the  last  few  years,  several  of  which  have  been  very 
successful.  Before  the  advent  of  the  modern  kerosene  engine 


70  FUELS 

much  difficulty  was  experienced  with  the  fuel  because  of  its 
high  vaporizing  temperature  and  its  tendency  to  carbonize  in 
the  cylinder,  but  as  the  price  of  gasoline  continued  to  rise,  the 
inventive  genius  of  the  gas  engine  builder  overcame  these 
troubles  so  that  the  kerosene  engine  is  now  as  reliable  as  any 
form  of  prime  mover. 


Kerosene    Vaporizer    on    Fairbanks-Morse    Engine.      The    Engine    is    Started 
on   Gasoline  and   When    Hot,   the  Kerosene   Feed   is   Turned   on. 

Any  gasoline  engine  will  run  on  kerosene,  after  a  manner,  if 
the  engine  is  thoroughly  heated  to  insure  the  vaporization  of 
the  kerosene,  and  if  the  fuel  heated  in  the  carburetor.  Such  an 
arrangement  is  make-shift,  however,  and  is  not  productive  of 
good  results  in  continuous  service.  If  kerosene  is  to  be  used 
as  a  regular  fuel,  a  kerosene  engine  should  be  used  to  avoid 
vaporizing  and  carbonizing  difficulties  as  well  as  the  sooty, 
offensive  exhaust,  and  the  loss  of  fuel  represented  by  the  soot. 


FUELS  71 

Many  kerosene  engines  are  arranged  to  start  on  gasoline, 
and,  after  becoming  heated,  have  the  running  feed  of  kerosene 
admitted  through  a  three  way  valve.  The  gasoline  feed  is  then 
stopped. 

The  above  arrangement  admits  of  easy  starting  in  all  weathers 
and  temperatures. 

In  the  Diesel  engine  there  is  no  evaporating  of  fuel,  and  no 
deposits  of  carbon  because  of  the  high  temperature  of  the  com- 
bustion chamber.  With  engines  that  draw  the  mixture  of  vapor 
and  air  into  the  cylinder  there  are  several  methods  of  applying 
heat  to  the  liquid,  and  the  combustion  o£  the  vapor  thus  formed 
is  perfected  by  the  injection  of  water  into  the  combustion 


Kerosene     Vaporizer     on     Fairbanks-Morse     Vertical     Engine.       Started    on 
Kerosene   Directly   by   Heating   Vaporizer   with   Torch. 

chamber.  It  has  been  found  by  experiment  that  a  small  amount 
of  water  vapor  introduced  into  the  cylinder  of  a  kerosene  en- 
gine makes  the  engine  run  more  smoothly  and  prevents  a 
smoky  exhaust  and  carbon  deposits  in  the  cylinder.  The  water 
is  introduced  into  the  cylinder  through  an  atomizer  in  the  form 
of  a  mist  or  fog,  the  particles  of  water  being  in  a  very  finely 
subdivided  state. 

The  deposits  of  free  carbon  (soot)  caused  by  the  "cracking" 
or  decomposition  of  the  kerosene  vapor  before  ignition,  due  to 
the  high  temperature  of  the  cylinder,  are  burnt  to  carbon  dioxide 
by  the  oxygen  of  the  water  which  is  also  set  free  by  the  heat  of 
the  cylinder.  This  produces  an  odorless  gas  (CO2)  which  in- 
dicates complete  combustion.  Besides  the  increase  of  fuel  ef- 
ficiency due  to  the  water  vapor,  the  cylinder  is  more  thoroughly 
cooled  and  is  more  efficiently  lubricated  because  of  the  reduc- 
tion in  temperature. 


CHAPTER  IV 
INDICATOR  DIAGRAMS 

GENERAL  DESCRIPTION.  An  indicator  is  an  instrument 
used  for  measuring  and  recording  the  pressures  in  a  gas  engine 
cylinder.  It  traces  a  scale  diagram  on  a  piece  of  paper  from 
which  it  is  possible  to  directly  determine  the  valve  setting, 
ignition  timing,  or  pressure.  By  a  few  calculations  it  is  possible 
to  use  it  in  obtaining  the  power  developed  within  the  cylinder. 
The  indicator  consists  essentially  of  a  small  cylinder  connected 
with  the  gas  engine  cylinder.  Variations  in  the  engine  cylinder 
pressure  cause  the  indicator  piston  to  trace  a  line  whose  height 
is  proportional  to  the  gas  pressure.  The  indicator  piston  works 
against  a  spring  of  known  tension. 

The  paper  on  which  the  diagram  is  traced  is  wrapped  around 
a  drum,  and  the  drum  is  connected  to  the  engine  piston  so  that 
it  is  turned  an  amount  corresponding  to  the  travel  of  the  piston. 
The  up  and  down  motion  of  the  pencil  caused  by  the  piston  of 
the  indicator,  combined  with  the  oscillation  of  the  drum  about 
its  axis,  produces  a  diagram  that  shows  the  pressure  variations 
in  regard  to  the  position  of  the  piston.  The  indicator  piston 
rises  and  falls  with  the  gas  pressure,  while  the  point  at  which 
any  event  takes  place  is  located  by  the  position  of  the  swinging 
drum.  The  "mean  effective  pressure"  or  the  average  pressure 
can  be  found  by  dividing  the  area  of  the  diagram  by  its  length, 
and  then  by  multiplying  this  quotient  by  the  number  of  pounds 
pressure  required  to  move  the  recording  pencil  one  inch. 

As  explained  in  a  former  paragraph  the  length  of  the  vertical 
lines  represents  certain  definite  pressures,  each  inch  of  length  rep- 
resenting so  many  pounds  as  per  square  inch,  the  exact  amount 
per  inch  depending  on  the  indicator  spring  strength  or  adjust- 
ment. To  make  this  point  clear,  all  of  the  indicator  diagrams 
shown  in  this  chapter  will  be  provided  with  a  scale  of  pressures 
at  the  left  of  the  diagram  by  which  the  pressure  at  any  point 
may  be  accurately  measured  off  for  practice.  It  should  be  noted 
that  points  on  the  curves  which  are  above  the  atmospheric  line 

72 


GAS,  OIL  AND  STEAM  ENGINES  73 

represent  positive  pressures  above  the  atmosphere,  and  that  the 
points  lying  below  the  atmospheric  line  represent  partial  vac- 
uums which  may  be  expressed  as_  being  so  many  pounds  per 
square  inch  below  the  atmosphere.  The  vacuum  pressures  in- 
dicate the  extent  of  the  "suction"  created  by  the  piston  when 
drawing  in  a  charge  of  air  and  gas. 

Straight  vertical  lines  show  that  the  increase  of  pressure  along 
that  line  has  been  practically  instantaneous  in  regard  to  the  pis- 
ton velocity,  for  if  the  pressure  increased  at  a  slow  rate  this 
line  would  be  inclined  toward  the  direction  in  which  the  pis- 
ton was  moving,  as  the  piston  would  have  moved  a  considerable 
distance  horizontally  while  the  pencil  was  moving  vertically. 
This  inclination  of  the  vertical  line  gives  an  idea  of  the  rate  at 
which  the  pressure  increases  in  relation  to  the  piston  speed, 
the  greater  the  inclination,  the  slower  is  the  rate  of  pressure  in- 
crease. Straight  horizontal  lines  that  lie  parallel  to  the  at- 
mospheric line  denote  a  constant  pressure  or  vacuum. 

The  rate  at  which  horizontal  lines  descend  or  incline  to  the 
atmospheric  line  represents  the  rate  at  which  the  pressure  in- 
creases or  decreases,  in  respect  to  the  piston  position  (not  piston 
velocity).  A  ste'ep  curve  represents  a  rapid  expansion  or  com- 
pression from  one  piston  position  to  the  next.  A  waving  or 
rippling  line  indicates  vibration  due  to  valve  chattering  or 
explosion  vibrations.  A  straight  inclined  line  shows  that  the 
pressure  is  decreasing  or  increasing  in  direct  proportion  to  the 
piston  position. 

(36)  Diagram  of  Four  Stroke  Cycle  Engine. 

By  referring  to  paragraph  25,  Chapter  III,  it  will  be  seen 
that  the  five  events  of  suction,  compression,  ignition,  expansion 
and  exhaust  are  accomplished  in  four  strokes,  in  the  following 
order: 

Stroke  1.     Suction — (Mixture  drawn  into  cylinder). 

Stroke  2.     Compression — (Mixture  compressed). 

0       *      *,   (  Ignition. 

Stroke  3.  \    *  ,        .  . 

^  Expansion  (working  stroke). 

Stroke  4.     Exhaust — (Scavenging  stroke). 

These  events  with  the  pressures  incident  to  each  drawn  to 
some  relative  scale  are  shown  graphically  in  Fig.  10  by  four 
lines  representing  the  four  strokes  of  the  piston.  In  order  to 
show  the  relation  between  the  diagram  and  the  piston,  a  sketch 
pf  the  cylinder  with  a  stroke  equal  to  the  length  of.  the  dia- 
gram is  shown  directly  beneath  the  curve.  The  vertical  line  IJ 


74 


GAS,  OIL  AND  STEAM  ENGINES 


Figs.    10-11-12.     Showing    Respectively    a    Typical    Four    Stroke    Diagram, 
Retarded   Combustion   and   Retarded    Spark. 


GAS,  OIL  AND  STEAM  ENGINES  75 

is  the  scale  of  pressures  (somewhat  exaggerated  in  order  that 
the  small  vacuum  and  scavenging  pressures  shall  be  clearly 
shown).  The  line  marked  "atmosphere"  represents  atmospheric 
pressure  and  it  is  from  this  line  that  all  measurements  of 
pressure  are  taken. 

Consider  the  piston  starting  on  the  suction  stroke,  the  piston 
moving  from  the  position  L  to  K,  or  from  left  to  right.  The 
movement  creates  a  partial  vacuum  in  the  combustion  chamber 
N  which  is  shown  on  the  diagram  as  the  distance  OA,  equal  to 
2  pounds  below  atmosphere  according  to  the  pressure  scale. 
The  suction  line  remains  at  this  distance  below  the  atmospheric 
line  until  within  a  short  distance  of  the  end  of  the  stroke  when 
it  rises  to  meet  the  atmospheric  line  at  B  when  the  piston 
reaches  the  end  of  the  stroke  at  K.  This  rise  at  the  end  of  the 
stroke  is  due  to  the  fact  that  the  piston  moves  more  slowly 
when  approaching  the  end  of  the  stroke  while  the  velocity  of 
the  incoming  gases  remains  nearly  constant  so  that  the  piston 
exerts  no  pull  nor  suction.  On  the  diagram  the  entire  suction 
stroke  is  represented  by  AB. 

The  piston  now  returns  on  the  compression  stroke  from  K  to 
J  compressing  the  mixture  in  the  combustion  chamber  N.  On 
the  diagram  this  stroke  is  shown  beginning  at  B,  with  the  pres- 
sure slowly  rising  until  the  pressure  is  a  maximum  at  the  point 
C  at  the  end  of  the  stroke.  During  the  compression,  the  pres- 
sure has  risen  from  that  of  the  atmosphere  at  B  to  125  pounds 
pressure  at  C  as  shown  by  the  scale.  At  a  point  slightly  before 
C  is  reached,  ignition  occurs,  and  the  pressure  rapidly  rises  from 
C  to  D,  due  to  the  expansion  of  the  heated  gas.  In  this  case 
the  combustion  is  practically  instantaneous  as  shown  by  the 
straight,  vertical  combustion  line  CD. 

At  D  the  piston  starts  on  the  working  stroke  from  left  to 
right  increasing  the  volume  of  the  gas  and  at  the  same  time  di- 
minishing the  pressure  because  of  the  expansion  until  the  maxi- 
mum pressure  of  400  pounds  per  square  inch  at  D  is  reduced  to 
30  pounds  per  square  inch  at  E,  the  line  DE  being  called  the  ex- 
pansion line.  During  this  time  the  heated  gas  has  been  perform- 
ing work  on  the  piston.  At  E  the  exhaust  valve  opens  and  the 
pressure  drops  from  E  to  T,  a  point  still  about  10  pounds  above 
atmospheric  pressure.  Theoretically  the  pressure  should  drop 
instantly  from  E  to  atmosphere,  or  from  30  pounds  per  square 
inch  to  zero,  but  practically  this  is  impossible  because  of  the 
back  pressure  due  the  slow  escape  of  the  exhaust  gases  through 
the  comparatively  small  valve  openings  and  exhaust  pipes. 


76  GAS,  OIL  AND  STEAM  ENGINES 

Since  considerable  pressure  is  exerted  by  the  piston  on  the 
return  stroke  in  forcing  the  gases  out  of  the  exhaust  valve,  the 
exhaust  line  TO  on  the  diagram  is  nearly  10  pounds  above  the 
atmospheric  pressure  from  T  to  O.  At  a  point  near  O,  the 
piston  slows  up  on  nearing  the  end  of  the  stroke  so  the  gases 
have  more  time  to  escape  through  the  valves,  and  the  pressure 
drops  to  the  atmosphere,  reading  for  the  succeeding  suction 
stroke. 

It  should  be  noted  that  the  points  A,  B,  E,  and  F  represent 
periods  of  valve  action.  At  A  the  inlet  valve  opens;  at  B 
the  inlet  closes;  at  E  the  exhaust  opens;  at  F  the  exhaust  closes, 
and  at  A  the  inlet  again  opens  at  the  beginning  of  the  suction 
stroke  AB.  That  this  is  true  is  apparent  from  the  fact  the 
inlet  must  open  at  the  beginning  of  the  suction  stroke,  and 
both  valves  must  be  closed  from  the  point  B  to  the  point  E 
in  order  to  prevent  the  escape  of  the  compressed  charge  and 
expanded  gases  from  the  cylinder.  At  the  end  of  the  working- 
stroke  the  exhaust  valve  must  liberate  the  gases  and  remain 
open  to  the  end  of  the  scavenging  stroke  to  eliminate  the 
residual  gas  while  the  closed  inlet  valve  prevents  the  burnt  gases 
from  being  forced  through  the  inlet  pipe  and  carburetor. 

As  shown  on  the  diagram,  the  exhaust  valve  closes  at  the 
same  time  that  the  inlet  opens,  as  F,  and  O  both  occur  on  the 
same  vertical  line  DL.  This  is  true  theoretically,  but  owing  to 
the  different  conditions  met  in  practice,  the  actual  setting  of 
the  valves  may  vary  slightly  from  that  shown  on  the  diagram. 
Some  makers  of  high  speed  engines  open  the  inlet  slightly  be- 
fore the  exhaust  clones  as  it  is  claimed  that  the  inertia  of  the 
exhaust  gas  passing  through  the  exhaust  pipe  creates  a  slight 
vacuum  that  is  an  aid  in  filling  the  cylinder  with  a  fresh  charge. 
It  should  be  borne  in  mind  that  this  condition  only  exists  when 
the  piston  has  come  to  rest  and  exerts  no  pressure  on  the 
exhaust  gas.  The  vacuum  is  due  to  the  velocity  inertia  of  the 
gas  after  it  has  been  reduced  to  atmospheric  pressure.  Other 
makers  close  the  exhaust  valve  a  very  little  before  the  inlet 
opens,  but  no  matter  what  the  setting,  the  difference  in  the  time 
of  opening  and  closing  is  very  small,  and  the  results  obtained 
probably  differ  by  an  almost  negligible  amount. 

During  the  suction  and  scavenging  strokes,  the  fly  wheel  of 
the  engine  is  expending  energy  on  the  gas  since  it  is  moving 
a  considerable  volume  at  a  fairly  high  pressure.  In  the  case 
of  the  scavenging  stroke,  the  piston  is  working  against  10 
pounds  back  pressure,  which  on  a  10  inch  piston  would  amount 


GAS,  OIL  AND  STEAM  ENGINES  77 

to  a  force  of  785  pounds.  With  the  2  pound  vacuum  the  drag 
on  the  piston  would  amount  to  157  pounds,  no  small  item  when 
the  velocity  of  the  piston  is  considered.  Of  course  the  pressure 
of  10  pounds  per  square  inch  is  rather  high,  but  it  is  often  at- 
tained with  long  and  dirty  exhaust  pipes.  It  is  items  of  this 
nature  that  cut  into  the  efficiency  of  the  engine,  and  increase 
the  fuel  bills,  and  it  is  only  by  the  indicator  that  we  can  de- 
termine the  extent  of  such  "leaks"  and  remedy  them. 

Since  the  area  of  the  indicator  card  represents  the  power  of 
the  engine,  it  is  evident  that  we  lose  the  power  represented  by 
the  area  included  in  the  rectangle  FEBO  on  the  scavenging 
stroke  plus  the  area  BOA  on  the  suction  stroke.  The  area  in- 
cluded in  BCO  represents  the  work  taken  from  the  engine  in 
compressing  the  charge,  but  this  is  returned  to  us  during  the 
next  stroke  plus  the  benefits  gained  by  compressing  the  mix- 
ture. The  arrows  show  the  direction  in  which  the  piston  is 
moving  during  that  event. 

An  actual  engine  does  not  follow  the  form  of  the  diagram 
shown  by  Fig.  10  exactly  because  of  certain  conditions  met  with 
in  practice  such  as  imperfect  mixtures,  faulty  valve  and  ignition 
timing,  small  valve  areas  or  leakage.  The  combustion  in  the  real 
engine  is  neither  instantaneous  nor  complete  but  it  approximates 
the  "IDEAL"  cycle  just  described  more  or  less  closely  with  a 
high  compression  and  a  fairly  well  proportioned  mixture. 

(37)  Detecting  Faults  With  the  Indicator. 

For  the  best  results  the  gas  must  be  completely  ignited  at  the 
point  of  maximum  compression,  and  the  pressure  must  be  estab- 
lished on  the  dead  center,  so  that  the  indicator  card  will  show 
a  straight  and  vertical  combustion  line.  As  all  gases  require  a 
certain  'length  of  time  in  which  to  burn,  the  ignition  should 
have  LEAD,  that  is,  should  be  started  before  the  end  of  the 
stroke  so  that  combustion  will  be  complete  at  dead  center.  The 
amount  of  ignition  lead  required  depends  on  the  fuel  and  the 
compression.  In  Fig.  10  the  point  of  ignition  (I)  is  shown  as 
occurring  before  the  end  of  the  compression  at  (C),  which 
insures  a  straight  combustion  line  CD. 

With  a  lean  or  slow  burning  gas,  that  is,  a  gas  slower  than 
used  on  the  diagram,  combustion  would  not  be  complete  at  the 
end  of  the  stroke  i'f  the  same  point  of  ignition  were  used.  This 
effect  is  shown  by  Fig.  (11),  in  which  the  full  line  diagram  BCDE 
represents  the  ideal  diagram  (Y),  and  BCFG  represents  the 
slow  burning  mixture  with  the  same  point  of  ignition  (X). 


78 


GAS,  OIL  AND  STEAM  ENGINES 


The  compression  curves  of  both  diagrams  are  coincident  as 
far  as  C,  the  ideal  diagram  shooting  straight  up  at  this  point 
and  the  weak  mixture  diagram  staying  at  the  same  level.  When 
under  the  influence  of  the  mixture  (X)  the  piston  starts  from 
left  to  right  and  reaches  the  point  F  before  the  slow  burning 
gas  reaches  its  maximum  pressure.  During  this  part  of  the 
stroke  there  has  been  very  little  pressure  on  the  piston  and  it 


Figs.    13-14.     The    First    Diagram    (13)    Shows    a    Two    Port    Two    Stroke 
Diagram,    the    Second  Shows   a   Typical   Diesel    Card. 

will  be  noticed  that  the  maximum  pressure  is  far  below  that  of 
the  ideal  diagram.  This  low  maximum  is  due  principally  to 
the  reduced  compression  under  which  the  gas  has  been  burn- 
ing, from  C  to  F. 

As  the  gas  has  but  a  small  part  of  the  stroke  left  in  which 
to  expand,  the  pressure  at  the  point  of  release  is  much  higher 
than  the  release  pressure  of  the  ideal  diagram,  which  means 
that  a  considerable  amount  'of  heat  and  pressure  have  been 
wasted  through  the  exhaust  pipe,  Besides  the  heat  loss,  the 


GAS,  OIL  AND  STEAM  ENGINES  79 

high  temperature  of  the  escaping  gas  has  a  bad  effect  on  the 
exhaust  valve  and  passage.  The  great  volume  of  gas  passing 
through  the  exhaust  valve  also  increases  the  back  pressure  on 
the  scavenging  stroke. 

Delayed  or  retarded  ignition  will  cause  a  low  combustion 
pressure  and  slow  combustion  with  any  type  of  fuel  or  compres- 
sion pressure  as  will  be  seen  from  Fig.  12.  In  this  case  the 
compression  pressures  of  the  ideal  diagram  Y  and  the  dia- 
gram X  showing  the  retarded  spark  are  of  course  the  same, 
the  compression  line  extending  from  B  to  C  in  the  direction  of 
the  arrows.  At  C  the  ignition  occurs  for  curve  Y,  and  the 
pressure  immediately  rises  to  D.  In  the  case  of  curve  X,  igni- 
tion does  not  occur  until  the  point  I  is  reached,  the  compres- 
sion falling  on  the  line  CI  with  the  forward  movement  of  the 
piston  as  far  as  the  point  I.  At  this  point  the  compression 
pressure  is  very  low  which  results  in  the  slow  combustion  in- 
dicated by  the  slant  of  the  combustion  line  IF.  The  point  of 
maximum  pressure  F  is  much  below  D  of  the  ideal  curve,  and 
as  there  is  no  opportunity  for  complete  expansion  during  the 
rest  of  the  stroke,  the  release  pressure  is  high  causing  a  great 
heat  loss.  If  running  on  a  LATE  or  RETARDED  spark  is 
continued  for  any  length  of  time  the  excessive  heat  that  passes 
out  of  the  exhaust  will  destroy  the  valves. 

It  is  apparent  that  for  the  best  results,  the  spark  should  occur 
slightly  before  ignition  in  order  to  gain  the  effects  of  the  com- 
pression, and  a  high  working  pressure  on  the  piston.  It  is  also 
evident  that  the  point  of  ignition  should  be  varied  for  different 
mixtures  that  have  different  rates  of  burning.  With  engines 
that  govern  their  speeds  by  throttling  or  by  changing  the 
quality  of  the  mixture  it  is  necessary  for  the  best  results,  to  vary 
the  point  of  ignition  with  each  quality  of  fuel  that  is  admitted 
by  the  governor.  The  retard  and  advance  of  the  ignition  is  very 
necessary  on  an  automobile  engine  because  of  the  throttling 
control  and  constant  variation  of  the  load  and  speed.  All  auto- 
mobilists  know  of  the  heating  troubles  caused  by  running  on 
a  retarded  spark. 

(38)  Two  Stroke  Cycle  Diagram. 

In  the  two  stroke  cycle  diagram,  the  lines  showing  the  suc- 
tion and  scavenging  strokes  are  missing  if  the  indicator  is  ap- 
plied only  to  the  working  cylinder. 

Starting  at  the  beginning  of  the  working  stroke  as  at  A  in 
Fig.  13,  the  gas  expands  during  the  working  stroke  until  the 


80  GAS,  OIL  AND  STEAM  ENGINES 

piston  uncovers  the  exhaust  port  at  B  where  the  pressure  drops 
to  C.  A  slight  travel  uncovers  the  inlet  port  with  .the  pressure 
still  above  atmosphere  due  to  the  pressure  in  the  crank  case 
filling  the  cylinder.  The  crank  case  pressure  continues  from 
C  to  D  or  to  the  end  of  the  stroke,  the  pressure  dropping 
slightly  at  the  latter  point. 

The  compression  stroke  now  takes  place  with  the  piston 
moving  from  right  to  left,  the  compression  pressure  reaching 
a  maximum  at  F.  Ignition  occurs  slightly  before  the  point  of 
greatest  compression,  at  I,  and  the  expanded  gas  increases  in 
pressure  until  the  point  A  is  reached.  From  this  point  the 
same  cycle  of  events  is  repeated.  Because  of  the  dilution  of 
the  charge  by  the  burnt  gases  of  the  preceding  combustion,  the 
mixture  burns  slowly  as  will  be  seen  from  the  inclined  combus- 
tion line  FA.  Due  to  this  delayed  combustion,  the  piston  travels 
the  distance  S  on  the  working  stroke  before  the  pressure  reaches 
a  maximum.  This  diagram  is  typical  of  the  small  marine  type 
of  two  stroke  cycle  engine  which  has  no  further  scavenging 
than  that  performed  by  the  rush  of  the  entering  mixture.  The 
diagram  of  the  pressures  and  vacuums  in  the  crank  case  are 
similar  to  those  of  suction  and  compression  in  the  four 
stroke  cycle  type. 

(39)  Diagram  of  Diesel  Engine. 

A  diagram  of  the  Diesel  engine  is  different  in  many  par- 
ticulars from  that  of  an  ordinary  gas  engine,  as  will  be  seen 
from  the  diagram  in  Fig.  14.  The  pressures  rise  in  an  even, 
gradual  line  from  the  end  of  the  compression  curve,  and  in- 
stead of  having  a  sharp  peak  at  the  end  of  the  combustion, 
as  in  a  gas  engine,  the  top  of  the  curve  is  broad  and  greatly 
resembles  the  indicator  diagram  of  a  steam  engine.  The  com- 
pression curve  constitutes  a  greater  proportion  of  the  pressure 
line  than  that  of  a  steam  engine,  the  rise  of  pressure  due  to 
the  ignition  being  very  slight  in  comparison  to  the  height  of 
the  compression  curve.  There  is  no  explosion  in  the  usual 
sense  of  the  word,  only  a  slight  increase  in  pressure  as  dis- 
tinguished from  the  rapid  combustion  in  the  gas  engine. 

Starting  at  the  beginning  of  the  compression  stroke  at  H,  the 
pressure  of  the  pure  air  charge  increases  to  about  500  pounds 
to  the  square  inch  at  I,  the  point  at  which  the  fuel  is  injected. 
From  I  to  C  is  the  increase  of  pressure  due  to  the  combustion. 
The  pressure  stays  at  a  Constant  height  from  C  to  D  as  the  fuel 
supply  is  continued  between  these  points,  and  is  cut  off  when 


GAS,  OIL  AND  STEAM  ENGINES  81 

the  piston  reaches  the  position  D.  It  will  be  seen  that  the 
admission  of  the  fuel  through  the  distance  A  covers  a  consider- 
able proportion  of  the  working  stroke,  and  that  the  points  of 
fuel  injection  and  ignition  are  coincident. 

From  the  point  of  fuel  cut-off  at  D  expansion  begins  and  is 
continued  in  the  usual  manner  to  F,  the  point  of  release. 

When  the  load  is  increased,  the  period  of  oil  injection  is  also 
increased,  the  other  events  remaining  constant.  Should  the 
light  load  require  an  oil  injection  period  as  shown  by  A,  the 
greater  load  would  require  injection  for  the  period  B.  In  the 
latter  case,  the  expansion  line  would  be  E  G,  which  would  pro- 
duce a  diagram  having  a  greater  area  than  the  line  DF,  and 
there  would  be  a  great  increase  in  the  release  pressure  GH  as 
well. 

It  will  be  seen  from  the  diagram  that  the  quantity  of  air 
taken  into  the  cylinder  and  the  compression  pressure  remain 
constant  with  any  load,  and  that  for  this  reason  it  is  possible 
to  have  a  constant  point  of  ignition,  or  rather  point  of  fuel 
injection.  As  there  is  no  mixture  compressed,  there  are  no  dif- 
ficulties encountered  at  light  loads  due  *to  attenuated  mixtures. 
An  excess  of  air  over  that  required  to  burn  the  fuel  is  also 
present  at  every  load  within  the  range  of  the  engine.  For  the 
sake  of  simplicity,  the  suction  and  scavenging  lines  on  the 
Diesel  engine  have  been  omitted,  but  they  are  the  same  in  all 
respects  as  the  corresponding  lines  shown  in  the  diagram, 
Fig.  14. 

(40)  Gas  Turbine  Development. 

In  the  attempt  to  gain  mechanical  simplicity,  small  weight, 
and  diminutive  size  of  the  steam  turbine,  many  able  experi- 
menters have  endeavored  to  obtain  an  internal  combustion 
motor  in  which  the  energy  of  the  expanding  gas  is  converted 
into  mechanical  power  by  its  reaction  on  a  bladed  wheel,  but 
so  far  the  problem  is  far  from  being  solved.  In  1906  two  ex- 
perimental turbines  were  built  by  Rene  Armengand  and  M. 
Lemale,  of  the  constant  pressure  type,  one  of  which  developed 
30  Brake  horse-power  and  the  other  300  horse-power. 

A  25  horse-power  De  Laval  steam  turbine  was  altered  by 
Armengand  says  Dugald  Clerk  so  that  it  operated  with  com- 
pressed air  instead  of  steam.  The  compressed  air  was  passed 
into  a  combustion  chamber  together  with  measured  quantities 
of  gasoline  vapor,  and  the  mixture  was  ignited  by  an  incan- 
descent platinum  wire  as  it  entered  the  chamber,  thus  maintain- 


82  GAS,  OIL  AND  STEAM  ENGINES 

ing  a  constant  pressure  with  continuous  combustion.  Around 
the  carborundum  lined  combustion  chamber  was  imbedded  a 
coil  in  which  steam  was  generated  by  the  heat  of  the  burning 
gas,  the  steam  being  used  to  reduce  the  temperature  of  the  gas 
from  1800°  C  to  about  400°  as  it  issued  from  the  orifice  and  came 
into  contact  with  the  running  wheel.  The  working  medium  was 
therefore  composed  of  two  elements,  the  products  of  combus- 
tion and  the  ^  steam  at  the  comparatively  low  temperature  of 
400°  C. 

The  constant  pressure  maintained  in  the  combustion  chamber 
was  about  10  atmospheres,  and  the  hot  gases  were  allowed  to 
expand  through  a  conical  Lava  jet  in  which  the  expansion  pro- 
duced a  high  velocity,  and  reduced  the  temperature  of  the  fluid. 
At  this  reduced  temperature  and  high  velocity  the  gases  im- 
pinged upon  the  Laval  wheel,  and  rotated  the  wheel  in  the 
same  way  as  steam  would  have  done.  The  experiments  showed 
that  under  these  conditions  the  total  power  obtained  from  the 
turbine  separate  from  the  compressor  was  double  that  neces- 
sary to  drive  the  compressor. 

In  the  large  300  H.  P.  turbine  the  first  part  of  the  combus- 
tion chamber  was  lined  with  carborundum,  backed  by  sand, 
but  the  second  part  was  surrounded  by  a  coil  through  which 
water  was  circulated.  The  water  kept  the  temperature  of  the 
combustion  chamber  within  safe  limits,  and  after  absorbing 
heat,  it  passed  also  around  the  jet  nozzle,  and  was  discharged 
into  the  passage  leading  to  the  jet,  and  there  converted  into 
steam  by  the  hot  gases.  A  mixture  of  products  of  combustion 
and  steam  thus  impinged  upon  the  turbine  wheel.  The  ex- 
panding jet  was  arranged  to  convert  the  whole  of  the  energy 
into  motion  before  the  fluid  struck  the  wheel;  the  temperature 
was  thus  reduced  to  a  minimum  before  the  gases  touched  the 
blades.  Notwithstanding  this,  the  wheel  itself  had  passages 
through  which  cooling  water  flowed,  and  each  blade  was  sup- 
plied with  a  hollow  into  which  water  found  its  way.  In  the 
large  turbine  the  compressor  was  mounted  on  the  turbine 
spindle;  it  was  of  the  Rateau  type,  and  consisted  of  an  inverted 
turbine  of  four  stages,  which  delivered  the  compressed  air  finally 
to  the  combustion  chamber  at  a  pressure  of  112  Ib.  per  sq.  in. 
absolute.  The  efficiency  of  this  turbine  compressor  was  found 
to  be  about  65  per  cent.  The  total  efficiency  of  the  combined 
turbine  and  compressor  was  low,  as  the  fuel  consumption 
amounted  to  nearly  3.9  Ib.  of  gasoline  per  B.  H.  P.  hour.  An 
ordinary  gasoline  engine  with  a  moderate  compression  can 


GAS,  OIL  AND  STEAM  ENGINES  83 

readily  give  its  power  at  the  rate  of  0.5  Ib.  of  gasoline  per 
B.  H.  P.  hour.  The  combined  turbine  and  compressor  was 
stated  to  have  run  at  4,000  R.  P.  M.  and  to  have  developed  300 
H.  P.  over  and  above  the  negative  work  absorbed  by  the 
compressor. 

A  gas  turbine  in  which  there  was  no  compression  was  buHt 
in  the  following  year  by  M.  Karovodine  which  gave  1.6  horse- 
power at  a  speed  of  about  10,000  revolutions  per  minute. 

It  contained  four  explosion  chambers  having  four  jets  actuat- 
ing a  single  turbine  wheel,  which  wheel  was  of  the  Laval  type, 
about  6  inches  diameter,  having  a  speed  of  10,000  R.  P.  M.  The 
explosion,  chambers  were  vertical,  and  had  a  water  jacket  sur- 
rounding the  lower  end.  The  upper  portion  contained  the 
igniting  plug  on  one  side,  and  the  discharge  pipe  connecting 
with  the  expanding  jet  on  the  other.  In  the  lower  water- 
jacketed  part  there  was  provided  a  circular  cover,  held  in  place 
by  a  screwed  cap.  This  circular  plate  was  perforated  with 
many  holes,  and  it  carried  a  light  steel  plate  valve  of  the  flap 
or  hinging  type,  which  pulled  down  by  a  spring  contained  within 
the  admission  passage.  This  spring  could  be  adjusted,  and  the 
lift  of  the  valve  was  regulated  by  means  of  a  set  screw  passing 
diagonally  through  the  water  jacket.  Air  was  admitted  at 
one  side  by  a  pipe  leading  into  the  valve  inlet  chamber  and  a 
corresponding  passage  or  pipe  admitted  gasoline  and  air  or  gas 
to  mix  with  the  air  before  reaching  the  thin  plate  valve.  Ad- 
justing contrivances  were  supplied  in  both  air  and  fuel  ducts. 
To  start  the  apparatus,  an  air  blast  was  forced  through  the 
valve,  carrying  with  it  sufficient  gasoline  vapor  to  make  the 
mixture  explosive.  The  electrical  igniter  was  started,  and  the 
spark  kept  passing  continuously.  Whenever  the  inflammable 
mixture  reached  the  upper  part  of  the  combustion  chamber  igni- 
tion took  place,  and  the  pressure  rose  in  the  ordinary  way,  due 
to  gaseous  explosion.  The  gases  were  then  discharged  through 
the  pipe  and  nozzle  on  the  Laval  wheel.  The  cooling  of  the 
flame  after  explosion  and  the  momentum  of  the  moving  gas 
column  reduced  the  pressure  within  the  explosion  chamber  to 
about  2  Ib.  per  sq.  in.  below  atmosphere.  Air  and  gasoline 
vapor  then  flowed  in  to  fill  up  the  chamber,  and  as  soon  as  the 
mixture  reached  the  igniter,  explosion  again  occurred.  In  this 
way  a  series  of  explosions  was  automatically  obtained,  and  a 
series  of  gaseous  discharges  was  made  upon  the  turbine  wheel. 
Diagrams  taken  from  the  explosion  chamber  showed  a  fall  in 
pressure  during  suction  of  2  Ib.  per  sq.  in.;  ignition  occurred 


84 


GAS,  OIL  AND  STEAM  ENGINES 


while  the  pressure  was  low,  and  the  pressure  rapidly  rose  to 
about  1  1-3  atmospheres  absolute.  The  pressure  propelling  the 
gas  column  and  jet  was  thus  only  5  Ib.  per  sq.  in.  above  at- 
mosphere. The  pressure  rapidly  fell,  and  the  whole  process 
was  repeated  again.  According  to  the  diagrams  taken,  a  com- 
plete oscillation  required  about  0.026  second,  so  that  about  40 
explosions  per  second  were  obtained. 

The  most  promising  type  of  turbine  that  has  been  built  to 
date  is  that  designed  by  Hans  Holzwarth,  an  engineer  of 
some  prominence  in  the  steam  turbine  field.  A  1000  horse- 


Fig.    15.     Cross-Section    of    the    Combustion    Chamber    of    the    Holzworth 
Gas    Turbine.     From    the    Scientific    American. 

power  machine  has  been  built  at  this  writing  and  as  ex- 
perimental machines  go  has  made  most  remarkable  performance. 
The  turbine  in  general  arrangement  outwardly  resembles  the 
Curtis  steam  turbine,  in  that  the  turbine  wheel  rotates  in  a 
horizontal  plane,  the  spindle  or  shaft  is  vertical  and  a  dynamo 
is  mounted  on  this  spindle  above  the  turbine.  In  the  Holzwarth 
turbine  ten  combustion  chambers  are  provided,  each  of  a  pear 
or  bag  shape.  They  are  arranged  in  a  circle  around  the  wheel, 


GAS,  OIL  AND  STEAM  ENGINES  85 

and  are  cast  so  as  to  form  the  base  of  the  machine.  The  wheel 
is  of  the  Curtis  type,  with  two  rows  of  moving  and  one  row 
of  stationary  blades. 

In  this  turbine  the  energy  of  the  fuel  is  liberated  intermit- 
tently by  successive  explosions,  instead  of  by  continuous  com- 
bustion, and  in  much  the  same  way  that  the  explosions  occur  in 
a  reciprocating  engine.  Tests  made  on  the  new  machine  have 
shown  that  it  is  in  no  way  inferior  in  efficiency  to  the  ordinary 
type  of  motor,  and  that  at  full  load,  the  weight  per  horse-power 
is  only  about  one-quarter  of  that  of  the  reciprocating  engine. 
The  weight  factor,  as  is  well  known,  is  of  the  utmost  im- 
portance in  marine  service  and  should  prove  of  value  to  the 
marine  engineer,  if  this  alone  were  its  only  characteristic. 

Any  of  the  ordinary  power  gases  may  be  used  with  success, 
as  well  as  vaporized  liquid  fuels,  and  the  lower  grade  oils  such 
as  crude  and  kerosene  have  given  much  better  results  in  the 
turbine,  than  in  reciprocating  engines,  even  at  this  early  stage 
of  its  development.  As  the  heat  losses  are  much  smaller  than 
met  with  in  ordinary  practice,  the  temperature  is  higher,  which, 
of  course,  greatly  facilitates  the  vaporization  of  the  lower  grade 
liquids. 

Mr.  Holzwarth  does  not  give  the  dimensions  of  his  turbine 
wheel,  but  from  the  drawings  and  some  of  the  velocities  given 
by  him  it  appears  to  be  about  1  m.  in  external  diameter.  The 
lower  part  of  each  combustion  chamber  carries  gas  and  air  inlet 
valves,  and  the  upper  part  carries  a  nozzle  arranged  to  cause 
the  gases  to  impinge  upon  the  first  row  of  moving  blades.  This 
nozzle  is  connected  to  and  disconnected  from  the  combustion 
chamber  by  means  of  an  ingeniously  operated  valve.  The  ex- 
plosion chambers  are  charged  with  a  mixture  of  gas  and  air, 
which  appears  to  attain  a  pressure  of  about  two  atmospheres 
within  the  chamber  before  explosion.  The  air  and  gas  are 
supplied  under  sufficient  pressure  from  turbine  compressors, 
actuated  by  steam  raised  from  the  waste  heat  of  the  explosion 
and  the  gases  of  combustion,  so  that  whatever  work  is  done  in 
compression  is  obtained  by  this  regenerative  action,  and  does 
not  put  any  negative  work  upon  the  turbine  itself.  The  com- 
bustion chambers  are  fired  in  series,  by  means  of  high-tension 
jump  spark  ignition. 

Referring  to  the  cut,  the  explosion  chamber  A  is  filled  in- 
termittently with  the  explosive  mixture  at  a  low  pressure  (about 
8  to  12  pounds  per  square  inch).  When  ignition  has  occurred, 
the  pressure  of  explosion  opens  the  nozzle  valve  F,  allowing 


86  GAS,  OIL  AND  STEAM  ENGINES 

the  compressed  gases  to  flow  through  the  nozzle  G  to  the  bladed 
turbine  H,  on  which  the  energy  is  to  be  expended.  The  ex- 
pansion of  the  heated  gases  in  the  nozzle  reduces  the  pressure 
to  that  of  the  exhaust,  with  the  resulting  increase  in  the  velocity 
of  the  gas.  By  means  of  fresh  air,  the  nozzle  valve  F  is  kept 
open  throughout  the  expansion  and  scavenging  periods. 

After  the  expansion  has  been  completed,  the  air  that  is  forced 
through  the  valve  D,  at  a  low  pressure,  thoroughly  scavenges  or 
removes  the  residual  burned  gases  left  in  the  combustion  cham- 
ber and  nozzle,  forcing  it  into  the  exhaust.  When  the  scaveng- 
ing has  been  completed,  the  nozzle  valve  and  the  air  valve  D 
are  closed.  The  combustion  chamber  A  is  now  filled  with 
pure  cold  air,  which  not  only  enables  a  fresh  charge  of  gas  to 
be  introduced  into  the  chamber  but  which  also  aids  in  keeping 
the  chamber  cool. 

Pure  fuel  gas,  or  atomized  oil,  is  now  injected  through  the 
fuel  valve  E,  forming  an  explosive  mixture  ready  for  the  en- 
suing cycle  of  events.  A  number  of  these  chambers  are  ar- 
ranged around  the  turbine  wheel  in  order  to  have  a  uniform 
application  of  power,  by  having  the  several  chambers  working 
intermittently.  This  is  in  effect,  the  same  proposition  as  in- 
creasing the  number  of  cylinders  on  a  reciprocating  engine. 


CHAPTER  V 
TYPICAL  FOUR  STROKE  CYCLE  ENGINES 

(41)  Essential  Parts  of  the  Gas  Engine. 

On  all  gas  engines  of  accepted  type  are  found  certain  devices 
necessary  for  the  performance  of  the  events  or  cycles  outlined 
in  the  preceding  section. 

For  the  sake  of  simplicity  these  devices  are  treated  as  a  part 
complete  in  itself.  The  details  of  construction,  and  the  refine- 
ments found  necessary  in  the  actual  construction  will  be  de- 
scribed in  the  succeeding  chapters. 

The  names  and  purpose  of  these  essential  components,  and 
their  relation  to  the  operation  of  the  engine  as  a  whole,  will  be 
found  in  the  following  outline: 

1.  The    CARBURETOR   is    a    device    whose   purpose    is    to 
vaporize  the  liquid  fuel,  and  mix  the  vapor  thoroughly  and  in 
correct  proportions  with   the  air  required   for  the   combustion, 
in  the  engine  cylinder. 

The  combustible  mixture  thus  formed  is  drawn  into  the 
cylinder  of  the  four  stroke  cycle  engine  or  into  the  crank  cham- 
ber of  the  two  stroke  cycle  engine. 

GENERATOR  VALVES  or  MIXING  VALVES  are  similar 
to  the  carburetor  in  principle  but  are  slightly  different  in  detail. 

2.  The   CYLINDER  is   the  containing  vessel  in  which   the 
combustion  and  expansion  of  the  gas  takes  place. 

The  cylinder  as  its  name  would  suggest  has  a  circular  open- 
ing or  bore  extending  from  end  to  end,  the  bore  being  smoothly 
finished  to  receive  the  reciprocating  piston. 

3.  The  PISTON  is  a  plunger  or  movable  plug  fitting  the 
bore  closely  enough  to  prevent  the   escape  of  gas,  but  at  the 
same  time  is  capable  of  sliding  freely  to   and  fro. 

When  pressure  is  established  in  the  cylinder  from  the  com- 
bustion, pressure  is  also  exerted  on  the  end  of  the  piston  tend- 
ing to  force  it  out  of  the  cylinder.  The  extent  of  this  force  is 
governed  by  the  area  of  the  end  of  the  piston  and  also  by  the 
pressure  of  the  gas. 

87 


88  GAS,  OIL  AND  STEAM  ENGINES 

Thus  the  purpose  of  the  piston  is  to  convert  the  pressure  of 
the  expanding  gas  into  direct  mechanical  force,  and  also  to 
transform  the  increasing  volume  of  gas  into  motion.  Another, 


Piston   and  Connecting   Rod  of  the   Sturtevant  Aero  Motor,    Showing  Three 
Piston   Rings. 

and  no  less  important  function  of  the  piston  is  to  compress  the 
combustible  gas  in  the  upper  end  of  the  cylinder  for  ignition. 

4.,  The  CONNECTING  ROD  (Sometimes  called  the  Pit- 
man) transmits  the  pressure;  on  the  piston  to  the  crank,  the 
connecting  rod  being  the  means  through  which  the  to  and  fro 
motion  of  the  piston  is  transmitted  into  the  rotary  motion  of  the 
crank;  its  action  being  similar  to  that  of  the  human  arm  turn- 
ing the  crank  of  a  pump  or  windlass. 

5.  The  CRANK  receives  the  pressure  and  motion  of  the 
piston  from  the  connecting  rod,  changing  the  reciprocating  mo- 
tion of  the  piston  into  the  rotary  motion  required  by  the 
machinery  which  the  engine  drives. 

In  the  majority  of  cases  the  crank  revolves,  while  the  cylinder 
stands  still,  but  in  some  of  the  recently  developed  aeronautic 
motors  this  is  reversed,  the  cylinders  revolving  with  the  crank 
stationary.  The  relative  motion,  however,  is  the  same  in  both 
cases. 

(6.)  The  CRANK  SHAFT,  of  which  the  crank  is  an  integral 
part,  transmits  the  rotary  motion  of  the  crank  to  the  driving 
pulley. 

(7.)  The  admission  and  release  of  the  gases  to  and  from  the 
cylinder  are  controlled  by  the  INLET  VALVE  and  EXHAUST 
VALVE,  respectively,  in  a  four  stroke  cycle  engine. 

The  valves  are  merely  gates,  allowing  the  gas  to  flow,  or 
stopping  it,  at  the  proper  intervals,  depending  on  the  event 
taking  place  at  that  time  in  the  cylinder. 


GAS,  OIL  AND  STEAM  ENGINES  89 

In  the  two  stroke  cycle  engine  there  are  no  valves,  the  ad- 
mission and  release  of  the  gas  being  controlled  by  the  position 
of  the  piston,  and  the  openings  cut  in  the  cylinder  walls. 

6.  IGNITION  or  the  firing  of  the  combustible  charge  is  ac- 
complished   by    the    IGNITION    SYSTEM.     In    most    modern 
engines  the   mixture  is  ignited  when  it  is  under  the   greatest 
pressure  or  at  the  end  of  the  stroke. 

For  maximum  efficiency  the  mixture  should  be  ignited  when 
it  is  under  the  greatest  pressure  or  compression.  The  time  at 
which  ignition  occurs  is  also  controlled  by  the  ignition  system. 

7.  The  GOVERNOR  regulates  the  speed  of  the  engine;  either 
by  changing  the  richness  of  the  mixture,  by  changing  the  num- 
ber   of   working    strokes    in    a    given    time    or    by    altering    the 
quantity   of  gas  admitted   to   the   cylinder,   or   sometimes   by   a 
combination  of  these  methods. 

8.  The   BELT  WHEELS   or  PULLEYS  are  the  means  of 
transmitting  the  power  of  the  engine  to  the  work  to  be  per- 
formed.    The  engine  is  generally  connected  to-  the  driven  ma- 
chinery by  a  belt  connecting  the  engine  pulley  with  the  pulley  of 
the  driven  machine. 

9.  The  FLY  WHEELS  by  reason  of  their  mass  and  their 
momentum,  store  up  a  portion  of  the  energy  expended  during 
the  working  stroke,  and  return  it  to  the  engine  in  order  to  carry 
it  through  the  idle  strokes  of  compression,   admission  and  ex- 
pulsion.    In   some   engines   the   fly  wheels   serve   in   double   the 
capacity  as  pulleys. 

10.  The  BASE  or  FRAME  of  the  engine  acts  as  a  foundation 
for   the   various   working   parts,    holding   them   in    their   proper 
positions. 

(42)  Application  of  the  Four  Stroke  Principle. 

While  the  five  events  of  every  commercial  four  stroke  cycle 
engine  are  accomplished  in  exactly  the  same  order,  or  routine 
as  explained  in  paragraph  (8),  Chapter  3,  the  actual  design  and 
method  of  applying  the  cycle  varies  greatly  in  different  makes 
of  engines.  This  great  difference  in  the  details  of  construction 
often  makes  it  difficult  for  the  novice  to  identify  the  cycle  of 
operations  in  that  particular  engine.  The  different  forms  of 
valve  gears  that  are  used  to  perform  the  same  functions  in  the 
cycle  are  good  examples  of  the  variation  in  design,  some  makers 
using  the  poppet  or  disc  type,  some  the  sliding  sleeve,  and  others 
the  rotary  type. 

Multiple   cylinder   engines   vary   in   the   cylinder   grouping  or 


90 


GAS,  OIL  AND  STEAM  ENGINES 


Fig.   16.     Ball   Bearing  Crank   Shaft,   Pistons  and   Connecting  Rods  of  the 
"Maximotor,"    in    Their    Relative    Positions. 

arrangement,  the  arrangement  and  number  of  cylinders  depend- 
ing on  the  service  for  which  the  engine  is  intended,  the  amount 
of  vibration  permissible,  or  the  weight.  The  question  of  speed 
also  introduces  modifications  in  the  design,  but  no  matter  what 
valve  arrangement  is  adopted  or  what  grouping  of  cylinders  is 


GAS,  OIL  AND  STEAM  ENGINES  91 

used,  a  four  stroke  cycle  engine  performs  the  five  events  of 
suction,  compression,  ignition,  expansion  and  exhaust  in  four 
strokes,  in  each  and  every  cylinder.  With  the  exception  of  fuel 
injection  (which  in  reality  corresponds  to  the  ignition  event) 
in  the  four  stroke  Diesel  engine,  the  indicator  cards  of  all  four 
stroke  cycle  engines  passes  the  same  characteristics  as  the  dia- 
gram shown  in  Fig.  10. 

In  this  chapter,  the  engine  will  be  described  without  regard 
to  the  fuel  used,  or  to  the  means  adopted  in  vaporizing  it,  for 
the  vaporizing  appliances  are  considered  as  being  external  to 
the  engine  proper,  except  in  some  of  the  heavy  oil  engines,  and 
as  the  fuel  is  gasified  before  entering  the  cylinder  the  question 
of  fuel  does  not  affect  the  general  construction  of  the  engine. 
The  majority  of  engines  are  readily  converted  from  gasoline  to 
gas,  or  in  some  cases  kerosene,  by  changes  in  the  vaporizing 
device,  and  with  the  exception  of  changing  the  compression 
pressure,  little  further  alteration  is  needed.  Since  the  vaporiza- 
tion and  admission  of  the  heavier  oils,  such  as  crude  oil  and 
kerosene  has  a  more  intimate  relation  to  the  engine  than  the 
use  of  gasoline  or  gas,  the  heavy  oil  engines  will  be  described 
in  a  separate  chapter  in  order  that  the  process  of  oil  burning 
may  be.  more  fully  explained.  It  should  not  be  understood  that 
the  cycle,  or  principle  of  the  oil  engine  differs  from  that  of  any 
other  engine,  but  that  the  vaporizer  forms  such  a  close 
connection  with  the  engine  proper  that  they  must  be  described 
as  one  unit. 

(43)  Horizontal  Single  Cylinder  Engine. 

An  example  of  a  modern  single  cylinder  engine  operating  on 
the  four  stroke  cycle  principle  is  the  "Muenzel"  engine  shown 
in  Section  by  Fig.  17.  It  is  of  the  single  acting  type,  that  is, 
the  pressure  of  the  gases  acts  only  on  the  left  end  of  the  piston 
which  reciprocates  in  a  horizontal  direction.  Surrounding  the 
cylinder  in  which  the  piston  slides,  is  the  water  jacket  (shown 
by  the  short  horizontal  dashes)  which  keeps  the  cylinder  walls 
from  becoming  overheated  by  the  successive  explosions  of  the 
mixture.  The  cooling  water  is  pumped  into  the  jacket  through 
the  pipe  shown  over  the  cylinder,  and  flows  out  of  the  jacket 
through  an  outlet  near  the  bottom  of  the  cylinder. 

Both  the  inlet  and  exhaust  valves  are  situated  in  an  ex- 
tended portion  of  the  combustion  chamber  to  the  left  of  the 
piston,  the  upper  valve  being  the  inlet  and  the  lower  valve,  the 
exhaust.  The  valves  are  held  on  their  seats  by  means  of  coil 


Fig.    17.     Longitudinal    Section   Through   the    Muenzel    Horizontal    Engine. 


GAS,  OIL  AND  STEAM  ENGINES 


93 


springs  that  act  on  the  upper  ends  of  the  valve  springs.  Admis- 
sion of  the  explosive  mixture  is  controlled  by  the  upper  valve, 
and  the  release  of  the  burnt  gases  by  the  lower.  Pipes  at  the 
bottom  of  the  cylinder  marked  "Gas  Supply"  and  "Exhaust" 
convey  the  gases  to  and  from  the  inlet  and  exhaust  valves  re- 
spectively. 

The  inlet  valve,  and  the  inlet  valve  spring  are  held  in  one  unit 
by  a  removable  metal  housing  known  as  a  "Valve  Cage",  which 
is  arranged  so  that  the  cage,  valve,  and  spring  may  be  re- 
moved as  one  piece  from  the  cylinder  casting  when  the  valves 
need  attention  by  removing  a  few  bolts.  As  the  cage  is  directly 
over  the  exhaust  valve,  and  is  considerably  larger  in  diameter, 
it  is  possible  to  remove  the  exhaust  valve  through  the  opening 


Fig.    18.      Elevation    of    Muenzel    Engine    Showing    Lay    Shaft    and    Valve 
Connections. 

left  by  the  removal  of  the  inlet  valve  cage.  Both  valves  are 
surrounded  by  a  water  jacket,  as  are  the  passages  that  lead  to 
them. 

Both  the  inlet  and  exhaust  valves  are  opened  and  closed  at 
the  proper  moments  in  the  stroke  by  means  of  cams  mounted 
on  the  horizontal  cam  shaft  shown  by  Fig.  18  through  a  system 
of  levers.  The  cam  shaft  is  the  shaft  running  parallel  to  the 
engine  bed  from  the  crank-shaft  to  the  end  of  the  cylinder  and 
turns  at  one-half  the  speed  of  the  crank-shaft.  At  a  point 
directly  below  the  inlet  valve  in  Fig.  18,  will  be  seen  an  en- 
largement on  the  shaft  on  which  rests  the  rod  running  from  the 
inlet  valve  to  the  cam  shaft.  This  is  the  cam. 

A  cylindrical   casing  shown   above  the  cylinder  contains   the 


94  GAS,  OIL  AND  STEAM  ENGINES 

governor  which  maintains  a  constant  speed  at  all  loads  by  oper- 
ating a  valve  in  the  intake  pipe  which  varies  the  quantity  of 
mixture  entering  the  cylinder  in  proportion  to  the  load.  The 
governor  is  driven  from  the  cam-shaft  by  spiral  gears.  The 
igniter  which  furnishes  the  spark  for  igniting  the  gas  is  located 
between  the  two  valves  at  the  extreme  left  of  the  combustion 
chamber  (Fig.  17). 

It  should  be  noted  that  the  cylinder  head  which  closes  the 
left  end  of  the  cylinder,  and  which  carries  the  valves  is  separate 
from  the  main  body  of  the  cylinder.  By  unscrewing  the  bolts 
that  hold  it  to  the  cylinder,  the  head  may  be  removed  when 
it  becomes  necessary  to  remove  dirt  and  carbonized  oil  from 
the  combustion  chamber,  or  when  it  becomes  necessary  to  re- 
move the  piston.  The  cylinder  barrel  in  which  the  piston 
works  may  also  be  removed  through  the  opening  left  by  the 
piston  head  when  it  becomes  worn,  and  another  barrel  or  liner 
may  be  substituted,  thus  practically  renewing  the  engine  at  a 
small  fraction  of  the  cost  of  a  new  cylinder.  The  liner  is 
fastened  firmly  to  the  outer  cylinder  casting  at  the  left  but  is 
free  to  slide  back  and  forth  in  the  casting  at  the  right  hand  end, 
this  end  being  provided  with  a  packed  joint.  This  play  given 
to  the  liner  allows  it  to  expand  and  contract  freely  with  the  dif- 
ferent changes  of  temperature  without  causing  strains  either 
in  the  cylinder  or  in  the  liner. 

(44)  Multiple  Cylinder  Engines. 

Since  the  power  exerted  by  a  single  cylinder  four  stroke 
cycle  engine  is  intermittent,  the  explosive  force  exerted  on  each 
power  stroke  is  much  heavier  than  would  be  the  case  if  the 
power  application  were  continuous,  as  the  explosions  must  be 
heavier  to  compensate  for  the  idle  periods.  To  reduce  the 
strain  on  the  engine  and  the  vibration  as  well  and  to  obtain  an 
even  turning  moment  it  has  been  customary  to  provide  more 
than  one  cylinder  on  engine  of  over  10  horse-power  capacity. 
In  this  way  the  total  power  is  divided  among  a  number  of 
cylinders,  and  as  no  two  cylinders  are  under  ignition  at  any 
one  time  the  turning  moment  is  more  even,  the  vibration  is  less, 
and  the  strain  on  the  engine  is  considerably  reduced. 

Dividing  the  power  in  this  way  makes  it  possible  to  reduce 
the  weight  of  the  engine  as  less  material  is  required  to  resist 
the  strains  and  a  small  fly-wheel  may  be  used  because  of  the 
even  engine  torque.  In  order  to  gain  the  full  benefit  of  this 
reduction  in  weight,  the  builders  of  aeronautic  motors  have 


GAS,  OIL  AND  STEAM  ENGINES 


95 


carried  the  multiplication  of  cylinders  to  an  extreme,  the  An- 
toinette for  example  having  sixteen  cylinders.  Engines  having 
more  than  six  cylinders  exert  a  continuous  pull  as  the  impulses 
"overlap,"  that  is,  ignition  occurs  in  one  cylinder  before  another 
cylinder  in  the  series  ends  its  working  stroke.  The  greater  the 


F-12.     Six    Cylinder    Maximotor. 


number  of  cylinders,  the  more  continuous  will  be  the  torgue 
or  turning  moment.  The  multiple  cylinder  engine  may  be 
considered  as  a  group  of  single  cylinder  engines  connected  to- 
gether, and  receiving  their  fuel  from  a  common  source,  the  only 


Fig.    F-13.     Four    Cylinder    Buffalo    Motor    for    Marine    Service. 

difference   between   the   single   and   multiple  being  in  the  inlet 
and  exhaust  piping  and  the  ignition  system. 

As  a  single  cylinder  four  stroke  cycle  engine  has  one  working 
impulse  in  every  two  revolutions,  a  two  cylinder  engine  will 
have  an  impulse  for  every  revolution  as  there  are  twice  as 
many  impulses  in  the  same  time.  It  should  be  remembered 
that  the  number  of  impulses  given  per  revolution  by  a  four 


96  GAS,  OIL  AND  STEAM  ENGINES 

stroke  cycle  engine  is  equal  to  the  number  of  cylinders  divided 
by  two.  Thus,  a  six  cylinder  engine  has  6  -4-  2  =.  3  impulses 
per  revolution,  and  an  eight  cylinder,  8  -f-  2  =  4  impulses,  pro- 
viding of  course,  that  the  engine  is  single  acting. 

Arrangement  of  the  cylinders  varies  with  the  service  for 
which  the  engine  is  intended  and  the  perfection  of  balance  that 
is  required,  the  principal  arrangements  being  the  "V,"  the 
"upright,"  the  opposed,  the  "radial,"  "tandem,"  and  "twin." 
The  upright  engine  has  the  cylinders  all  on  one  side  of  the 
crank-shaft  in  a  straight  line,  as  in  the  four  cylinder  automobile 
engine.  In  this  form,  each  cylinder  has  an  individual  crank 
throw  the  number  of  throws  being  equal  to  the  number  of 
cylinders.  This  engine  is  fairly  well  balanced  in  the  four,  six 
and  eight  cylinder  types,  as  one-half  of  the  connecting  rods  and 
throws  are  up,  while  the  other  half  are  down,  but  as  the  con- 
necting rods  do  not  all  make  equal  angles  with  the  center  line 
of  the  cylinder  at  the  same  time  there  is  a  slight  unbalance  in 
the  four  and  six  cylinder  types.  Because  of  the  ignition  se- 
quence, two  cylinder  vertical  motors  are  in  no  better  balance 
than  the  single  cylinder  type  since  both  crank  throws  and  con- 
necting rods  are  on  the  same  side  of  the  shaft  at  the  same  time. 
For  this  reason  the  two  cylinder  engine  is  most  commonly  built 
in  the  opposed  type  which  gives  perfect  balance. 

In  "V"  type  arrangement,  one-half  of  the  cylinders  are  set 
at  an  angle  of  about  90°  with  the  rest  of  the  cylinders,  or  in 
the  two  cylinder  "V"  the  cylinders  are  set  in  the  same  plane, 
perpendicular  to  the  shaft,  at  angle  varying  from  57y2°  to  90°. 
The  "V"  type  arrangement  is  adopted  where  light  weight  and 
compactness  are  the  principal  requirements,  as  the  weight  and 
length  are  both  reduced  by  putting  the  cylinders  opposite  to 
one  another  by  pairs,  the  "V"  being  practically  one-half  the 
length  of  an  upright  having  the  same  number  of  cylinders. 
This  arrangement  permits  the  use  of  one-half  the  number  of 
crank  throws  used  in  the  vertical  type  as  each  crank  throw 
acts  for  two  cylinders.  For  the  reason  that  both  the  cylinders 
of  a  two  cylinder  "V"  act  on  a  common  crank  throw,  the  two 
cylinder  "V"  is  in  no  better  balance  than  a  single  cylinder 
engine. 

An  "opposed"  type  engine  is  in  the  most  perfect  mechanical 
balance  of  any  engine  as  the  crank  shafts  and  connecting  rods 
are  not  only  on  opposite  sides  of  the  crank-shaft,  but  make 
equal  angles  with  the  center  line  of  the  cylinders  as  well,  at  all 
points  in  the  revolution.  '  The  explosive  impulses  occur  at  equal 


GAS,  OIL  AND  STEAM  ENGINES 


97 


•C  V        . 
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ou  « 

c8      jn  c  •<-• 


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98  GAS,  OIL  AND  STEAM  ENGINES 

angles  in  the  revolution  as  in  the  four  and  six  cylinder  vertical 
type.  An  opposed  engine  may  be  considered  as  a  "V"  having 
a  cylinder  angle  of  180°.  In  the  opposed  type,  one  crank  throw 
is  provided  for  each  cylinder,  the  pistons  of  the  opposite  cyl- 
inders traveling  in  opposite  directions  at  the  same  time. 

A  "radial"  or  "Fan"  type  motor,  as  the  name  would  suggest 
has  the  cylinders  arranged  in  one  or  two  rows  around  the 
crank  case,  each  cylinder  being  on  a  radial  line  passing  through 
the  center  of  the  cylinder  with  one  crank  throw  for  each  row. 
The  Gnome  engine  illustrated  elsewhere  in  the  book  is  an  ex- 
ample of  this  type,  the  seven  equally  spaced  cylinders  acting 
on  a  common  crank  throw.  When  more  than  seven  cylinders 
are  used  on  this  engine,  as  in  the  fourteen  cylinder  engine,  two 
cranks  are  provided,  each  crank  serving  seven  cylinders.  This 
arrangement  cuts  down  the  weight  of  a  motor  enormously  be- 
cause of  the  short  crank  shaft  and  case.  With  the  ignition 
properly  timed  and  the  cylinders  correctly  spaced  the  firing  im- 
pulses occur  at  equal  angles. 

"Tandem"  cylinders  are  employed  only  on  stationary  engines, 
the  cylinders  being  placed  on  the  same  center  line,  one  in  front 
of  the  other,  and  when  this  arrangement  is  adopted  it  is  the 
usual  practice  to  make  the  cylinders  double  acting.  The  two 
pistons  are  connected  by  a  rod  known  as  the  "piston  rod"  which 
extends  from  the  rear  end  of  one  cylinder  into  the  front  of  the 
following  cylinder.  Tandem  cylinders  require  too  much  room 
for  use  on  automobiles  or  motor  boats,  and  for  this  reason  are 
seldom  seen  in  this  service. 

The  "twin"  engine  is  a  modification  of  the  vertical  cylinder 
arrangement,  both  cylinders  being  on  the  same  side  of  the 
shaft  and  in  line  with  one  another.  It  is  the  type  most  gen- 
erally used  oh  very  large  stationary  engines  that  have  more 
than  one  cylinder,  and  instead  of  being  vertical  as  in  their 
prototype  are  generally  laid  horizontally.  Since  the  twin  en- 
gine is  generally  double  acting,  the  crank  throws  are  placed  on 
opposite  sides  of  the  shaft. 

(45)  Pour  Cylinder  Vertical  Auto  Motor. 

A  common  type  of  four  cylinder  vertical  motor  is  shown  by 
Fig.  19,  which  is  of  the  type  commonly  used  on  automobiles.  In 
order  to  show  the  general  construction  of  the  cylinder,  each 
cylinder  is  cut  through  at  a  different  point.  The  cylinder  at  the 
extreme  left  is  shown  in  elevation,  or  as  we  would  see  it  from 
the  outside.  In  the  second  cylinder  from  the  left,  the  section 


GAS,  OIL  AND  STEAM  ENGINES  99 

is  taken  through  the  valve  chamber,  which  projects  from  the 
side  of  the  cylinder.  A  section  through  the  center  of  the  cyl- 
inder is  shown  on  the  third  cylinder,  and  the  fourth  cylinder  is 
in  elevation. 

On  cylinder  No.  1,  (left)  is  seen  the  exhaust  pipe  (32)  and 
the  inlet  pipe  (31)  entering  to  valve  chamber  and  connected 
to  the  exhaust  valve  and  inlet  valve  respectively.  The  pipes 
are  held  in  place  by  the  clamp  or  "crab"  (33).  The  exhaust 
pipe  connects  with  the  exhaust  valve  of  each  cylinder,  and 
terminates  at  the  fourth  cylinder  as  shown  by  (32).  Screwed 
into  the  top  of  the  valve  chamber  on  cylinder  No.  1  are  the 
two  spark  plugs  (34)  and  the  relief  cock  (35). 

Referring  to  cylinder  No.  2,  the  inlet  valve  (42)  is  shown  at 
the  left  of  the  chamber  and  the  exhaust  valve  also  shown  by 
(42)  is  shown  at  the  right.  Above  the  valves  are  the  spark 
plugs  (34)  which  project  into  the  space  above  the  valves.  Press- 
ing against  the  lower  ends  of  the  valve  stems  and  holding  the 
valves  tight  on  their  seats  are  the  springs  (44)  which  fit  into  the 
washers  (45)  fastened  to  the  stems.  The  valve  stems  terminate 
in  a  nut  at  (48).  The  valve  stem  guides  (43)  form  a  support 
for  the  valves  and  at  the  same  time  form  an  air  tight  connec- 
tion for  the  stems  to  slide  in. 

Immediately  beneath  the  stems  are  the  push  rods  (46)  which 
are  provided  with  an  adjustment  (48)  at  the  upper  end,  and  a 
roller  (49)  at  the  lower  end.  The  rollers  (49)  rest  directly 
on  the  cams  mounted  on  the  cam  shaft  (27),  and  as  the  irreg- 
ular cams  revolve,  the  push  rods  are  moved  up  and  down  which 
in  turn  act  on  the  valve  stems  and  raise  the  valves  at  the  proper 
moment.  The  cams  raise  the  valves  and  the  springs  close  them. 
The  two  cams  (exhaust  and  inlet)  appear  as  two  rectangular 
enlargements  on  the  shaft  (27).  The  bearings  (53),  support 
the  cam  shaft,  one  being  supplied  for  each  cylinder. 

At  the  extreme  left  of  the  crank  shaft  is  shown  the  half 
time  gear  (20)  which  meshes  with  the  gear  on  the  crank-shaft 
and  drives  the  cams.  Next  to  this  gear  is  the  large  cam  shaft 
bearing  26.  It  should  be  noted  that  the  section  through  the 
valve  chamber  taken  on  cylinder  No.  2  is  at  a  point  consider- 
ably back  from  the  center  line  of  the  cylinders  and  not  in  the 
same  plane  as  the  section  shown  on  cylinder  No.  3,  which  is 
taken  through  the  center  line  of  the  cylinders. 

In  the  section  of  cylinder  No.  3,  we  see  the  water  space  sur- 
rounding the  upper  portion  of  the  cylinder  with  the  opening 
(37)  connected  to  the  water  manifold  (36),  through  which  the 


100  GAS,  OIL  AND  STEAM  ENGINES 


Fig.     19.     Cr9ss-Section     Through     Typical     Four     Cylinder     Automobile 
Engine.      Courtesy    of    the    Chicago    Technical    College. 


GAS,  OIL  AND  STEAM  ENGINES  101 

water  leaves  the  cylinder  and  passes  to  the  radiator.  At  the 
lower  end  of  the  stroke  is  the  piston,  one-half  of  which  is 
shown  in  section  and  one-half  in  elevation  so  that  internal  and 
external  appearance  may  be  readily  seen.  The  piston  pin 
(60)  is  located  approximately  in  the  center  of  the  piston  to 
which  it  is  secured  by  means  of  the  set-screw  (61). 

By  means  of  the  connecting  rod  (56),  the  motion  of  the 
piston  is  transmitted  to  the  crank-shaft  throw  1^54),  both  ends 
of  which  are  provided  with  bronze  bushings  ^(59)  and  (58), 
fitting  on  the  piston  pin  and  crank-pin  respectively.'  JJ3fitweeaJ 
each  crank  throw  are  the  main  crank  shaft  ^e^fin'gs'  (5#)  which- 
are  provided  with  the  bronze  bushings  (54).  -B^lov^th-t  con- 
necting rod  ends  is.  the  small  drip  trough^  con  tailing"  oil 'intol 
which  the  pipes  on  the  rod  ends  dip  when  passing  around  the 
lower  end  of  the  stroke.  When  the  pipes  enter  the  oil  puddle 
a  small  amount  of  lubricating  oil  is  driven  into  the  crank-pin 
bearing  because  of  the  force  of  impact,  this  force  also  causing 
oil  to  splash  about  in  the  crank  case  for  the  lubrication  of  the 
main  crank  shaft  bearings  and  cam  shaft.  In  order  to  main- 
tain a  constant  level  of  oil  in  the  puddle  so  that  the  bearings 
shall  receive  a  constant  supply  of  oil,  a  small  overflow  opening 
is  placed  in  the  center  of  the  puddle  which  allows  an  excess  of 
oil  to  overflow  into  the  return  oil  sump  below. 

This  excess  of  oil  drains  by  gravity  back  to  the  oil  circulat- 
ing pump  (73),  at  the  right  which  again  forces  the  oil  to  the 
various  bearings.  In  this  way,  the  same  oil  is  used  over  and 
over  again  until  it  becomes  unfit  for  lubricating  purposes  be- 
cause of  dirt  or  decomposition.  The  oil  pump  is  driven  from 
the  cam-shaft  through  the  level  gears  (66)  and  the  vertical 
shaft  (72).  To  the  right  of  the  oil  pump  is  the  fly-wheel  (75) 
which  furnishes  the  power  for  the  idle  strokes  of  the  engine. 

At  the  upper  end  of  the  vertical  shaft  that  drives  the  oil 
pump  is  an  extension  (68)  which  passes  through  the  bearing 
(70)  and  drives  the  ignition  timer  shown  at  the  top  of  the 
housing  (69).  The  timer  controls  the  period  of  ignition  in  the 
cylinders  in  regard  to  the  piston  position  so  that  the  spark 
occurs  at  the  end  of  the  compression  stroke.  At  the  extreme 
left  of  the  engine  is  the  radiator  fan  (1)  which  is  driven  from 
the  crank-shaft  pulley  (16),  the  belt  (10),  and  the  fan  pulley 
(1122).  This  fan  increases  the  amount  of  cold  air  that  is  drawn 
through  the  radiator,  (mounted  to  the  left  of  the  engine)  and 
increases  its  capacity  for  cooling  the  jacket  water  of  the  en- 
gine. The  water  circulating  pump  is  located  on  the  opposite 
side  of  the  motor. 


102  GAS,  OIL  AND  STEAM  ENGINES 


WPS- 


N  m 


Fig.     19-a.     Buda     Four     Cylinder     Automobile     Motor.      Carburetor     Side. 


Fig.    19-b.      Buda    Motor,    Pump    Side,    Cylinders    "En    Bloc." 


GAS,  OIL  AND  STEAM  ENGINES 


103 


In  this  motor  both  the  inlet  and  exhaust  valves  are  located 
on  the  same  side  of  the  cylinder  which  arrangement  classifies 
the  engine  as  an  "L"  type,  the  extended  valve  pockets  forming  an 
"L"  with  the  center  line  of  the  cylinder.  In  the  motor  shown 
by  Figs.  F-14 — F-15,  the  inlet  and  exhaust  valves  are  on  opposite 
sides  of  the  cylinder  as  shown  in  the  "cross-section,  which  classi- 
fies the  motor  as  a  "T"  type,  as  the  valve  chambers  together 
with  the  cylinder  forms  a  "T."  The  latter  type  of  motor  has 


Fig.    F-14.     Cross-Section   Through    Wisconsin    Truck   Motor.      "T"    Type. 

several  advantages  over  the  "L"  type,  but  as  it  requires  two 
cam  shafts,  one  for  the  inlet  and  one  for  the  exhaust  valves, 
it  is  not  adopted  by  the  builders  of  the  cheaper  grades  of 
automobiles.  Since  the  exhaust  valves  are  on  the  opposite 
side  of  the  cylinder,  in  the  "T"  type,  the  inlet  air  is  not  ex- 
panded nor  the  output  diminished  by  the  heat  of  the  exhaust 
passages.  The  piping  is  less  complicated  which  permits  of  a 
more  effective  arrangement  of  the  carburetor  and  magneto. 
Since  the  piping  in  the  latter  type  can  be  arranged  to  better 
advantage,  less  back  pressure  is  the  result. 


104 


GAS,  OIL  AND  STEAM  ENGINES 


As  in  the  previous  case,  the  valves  are  acted  on  directly  by 
the  cams  and  push  rods,  one  cam  shaft  being  provided  on  each 
side  of  the  cylinders.  In  order  to  reduce  the  noise  made  by 
the  push  rods  and  springs,  all  of  the  springs  are  enclosed  by 


F-15.      Longitudinal    Through    Wisconsin    Truck    Motor. 


sheet  metal  housings  or  tubes.  The  circulating  pump  is  shown 
at  the  left  nearly  on  a  line  with  the  left  hand  cam  shaft,  the 
pump  outlet  being  inclined  toward  the  cylinder  so  that  it 
enters  the  water  jacket  under  the  exhaust  valves.  Water 
leaves  the  jacket  by  the  pipe  shown  on  the  cylinder  tops. 


GAS,  OIL  AND  STEAM  ENGINES 


105 


From  the  longitudinal  section  it  will  be  seen  that  the  cylin- 
ders are  cast  in  pairs,  two  cylinders  to  the  pair,  instead  of 
singly  as  in  the  previous  case.  The  large  pipe  crossing  at 
about  the  center  of  the  cylinders  is  the  exhaust  pipe  (shown 
in  front  of  the  left  pair),  and  the  pipe  shown  under  the 
exhaust  is  the  water  inlet  pipe  from  the  circulating  pump.  It 
will  be  seen  from  the  longitudinal  section  that  the  main 
crank-shaft  bearings  are  fastened  to  the  upper  half  of  the 
crank  case,  and  are  entirely  independent  of  the  lower  half 
which  acts  simply  as  an  oil  shield.  This  construction  allows 


Six    Cylinder    Rutenber    Automobile    Motor,    with    Cylinders    Cast   in    Pairs. 

the  oil  shield  (lower  half)  to  be  removed  without  disturbing 
the  adjustment  of  the  bearings,  when  it  becomes  necessary 
to  inspect  the  internal  mechanism. 

Large  removable  plates  cover  the  top  of  the  water  jackets 
so  that  it  is  a  simple  matter  to  clean  out  the  water  space  in  case 
that  it  becomes  coated  with  deposits  from  the  water.  This 
is  an  important  feature  as  a  great  many  of  the  heating  troubles 
may  be  overcome  by  having  access  to  the  interior  of  the  water 
jacket.  The  water  outlet  pipes  connect  with  the  jacket  covers. 
Both  cam  shafts  are  driven  by  the  gears  at  the  right  which 
connect  with  the  crank  shaft  pinion.  Fan  is  belt  driven  from  an 
extension  to  the  cam  shaft. 

All  bearings  are  supplied  with  oil  by  a  high  pressure  force 
feed  pump,  the  crank  pins  receiving  their  supply  through 


106 


GAS,  OIL  AND  STEAM  ENGINES 


channels  drilled  in  the  crank  shaft  and  pin,  which  in  turn  are 
connected  to  the  oil  supply  of  the  main  bearings,  no  dependence 
being  placed  on  a  splash  system.  After  leaving  the  bearings, 
the  oil  drops  into  the  crank  case  and  drains  into  the  sump 
shown  at  the  left  of  the  longitudinal  section.  From  the  sump, 
the  oil  returns  to  the  oil  pump  from  which  point  it  is  returned 
to  the  circulating  system  under  high  pressure. 

(46)  Stationary  Four  Cylinder  Engine. 

An    English    stationary    engine,    the    Browett-Lindly,    similar 
in  many  respects  to  the  automobile  engines  just  described,  is 


Fig.   21.     Cross-Section   Through  Browett-Lindly   Engine. 

shown  in  longitudinal  and  cross-section  by  Figs.  20  and  21. 
This  is  of  the  "L"  type  of  valve  arrangement,  but  instead  of 
having  the  valves  side  by  side  as  in  the  preceding  case,  the 
inlet  valve  is  placed  over  the  exhaust  as  will  be  seen  from  the 
cross-section  view. 

The  exhaust  valve  is  operated  directly  from  the  cam  shaft 
by  the  push  rod  as  in  the  auto  engines,  but  the  inlet  valve 
receives  its  motion  through  a  long  vertical  rod  and  horizon- 
tal lever,  the  latter  being  located  on  the  cylinder  head  as  shown 


GAS,  OIL  AND  STEAM  ENGINES 


107 


by  the  longitudinal  section.  A  supplementary  valve  is  mounted 
loosely  on  the  stem  of  the  inlet  valve,  and  this  valve  is  held 
against  the  seat  of  the  gas  inlet  port  by  a  short  spring. 

A  collar  on  the  main  valve  spindle  opens  this  gas  valve,  and, 
by  adjusting  the  position,  a  certain  amount  of  lag  can  be  given, 


Fig.     20.     Section     Through     Browett-Lindly     Four     Cylinder     Stationary 

Engine. 

so  that  air  first  enters  the  cylinder  and  then,  by  further  travel  of 
the  main  valve,  the  gas  valve  opens  and  the  combined  charge 
is  taken  in.  This  prevents  any  "back  fires"  as  the  gas  and 
air  are  entirely  separated  until  they  enter  the  cylinder. 


108  GAS,  OIL  AND  STEAM  ENGINES 

Starting  is  effected  by  means  of  compressed  air,  and  is  en- 
tirely automatic.  No  compression  release  is  provided,  as  this 
is  unnecessary  under  the  system  adopted.  By  opening  tne 
main  compressed  air  valve  compressed  air  is  admitted  to  two 
valve  boxes  placed  underneath  the  cam  shaft,  and  the  pressure 
of  air  raises  the  valves  against  their  levers  and  cams.  Should 
the  swell  on  the  cam  be  opposite  a  lever  as  it  will  be  in  the 
correct  starting  position,  the  valve  cannot  close,  and  the  com- 
pressed air  then  passes  to  the  cylinder  through  a  check  valve 
on  the  face  of  the  cylinder,  and  the  engine  starts.  The  auto- 
matic check  allows  the  cylinders  to  take  in  a  charge  of  mix- 


Fig.    21 -a.     Section    Through    Cylinder    of    Fairbanks-Morse    Type    "R  E" 
Engine,    with   Valves   in   the    Head. 

ture  on  the  second  stroke  and  firing  takes  place  immediately. 
When  the  explosion  pressure  is  greater  than  the  air  pressure 
the  check  remains  closed  and  no  more  starting  air  enters  the 
cylinder. 

Governing  is  effected  by  varying  both  the  quantity  and  qual- 
ity of  the  mixture. 

The  main  valve,  plunger,  and  rod  springs,  and  all  springs  on 
the  valves  and  valve  motion,  are  arranged  to  be  in  compression. 
The  exhaust  valves  are  of  cast-iron,  and  are  fitted  with  renew- 
able seats  in  the  cylinders.  The  admission  valves  are  of  nickel 
steel,  and  are  arranged  in  boxes,  which,  when  removed  from 
the  cylinders,  provide  the  ports  which  give  access  to  and  space 
for  the  removal  of  the  exhaust  valves  which  are  withdrawn 
vertically. 


GAS,  OIL  AND  STEAM  ENGINES 


109 


Forced  lubrication  is  fitted  throughout  all  bearings,  valves, 
plunger  guides,  governor,  cam  shaft,  etc.,  the  oil  under  pressure 
being  supplied  by  two  valveless  pumps,  either  of  which  is  sum- 
cient  to  maintain  the  working  pressure  of  oil. 

The  normal  output  of  the  engine  is  400  brake  horse-power, 
with  an  allowable  overload  of  40  horse-power  for  ^  hour.  The 
exhaust  pipe  is  water  jacketed,  each  section  being  supplied  from 
the  small  pump  shown  at  the  end  of  the  cross  section. 

Double  ignition  is  provided  for  an  emergency,  by  two  high 
tension  magnetos,  each  of  which  is  connected  to  a  separate  set 
of  plugs.  When  starting  the  engine,  an  ordinary  spark  coil  and 
storage  battery  are  used  until  the  engine  gets  up  to  speed, 
when  the  coil  is  cut  out  and  the  magneto  is  thrown  in. 

(47)  The  ''V"  Type  Motor. 

An  example  of  the  "V"  type  motor  is  shown  by  Fig.  22,  which 
is  a  front  elevation  of  the  Frontier  aeronautic  motor,  a  type 
that  occupies  a  minimum  of  space  with  a  minimum  of  weight. 

The  cylinders  are  cast  separately  and  are  furnished  either 
with  iron  or  copper  water  jackets,  the  copper  jackets  being 
deposited  over  the  cylinder  barrels  by  an  electrolytic  process 


Fig.    22.     End    Elevation    of    Frontier    8    Cylinder    "V"    Type    Motor. 


110  GAS,  OIL  AND  STEAM  ENGINES 

in  much  the  same  way  as  that  of  the  celebrated  French  Antoin- 
ette. Bolts  passing  through  flanges  on  the  bottom  of  the  cyl- 
inder fasten  them  to  the  base.  A  special  aluminum  alloy  is 
used  for  the  base  which  is  cast  in  a  single  piece  with  webs  to 
receive  the  bearings.  A  unit  crank-case  insures  perfect  align- 
ment, prevents  a  greater  part  of  the  oil  leakage,  and  forms  a 
much  stronger  construction  than  the  usual  split  pattern.  A 
chamber  is  provided  for  the  cam  shaft  at  the  apex  of  the  case 
through  which  issue  the  pusfr-rods.  Shafts  and  piston  pins  are 
hollow.  All  push  rods  are  adjustable  for  wear  and  have  steel 
balls  running  on  the  cams  which  eliminate  the  possibility  of 
mis-timing  through  wear. 

Lubrication  is  by  a  bronze  pump  geared  from  the  crank-shaft 
and  is  connected  to  an  oil  tank  located  in  the  base  from  which 
the  oil  is  forced  through  the  crank-shaft  up  through  the  hollow 
connecting  rods  to  the  piston  pins,  thence  to  the  cylinder 
walls,  the  surplus  returning  to  the  tank  in  which  the  strainer  is 
located. 

The  circulating  pump  is  driven  from  the  cam  shaft  as  shown 
in  the  cut  and  supplies  the  cylinders  and  radiator  with  water 
through  the  copper. water  manifolds  which  are  designed  to 
give  an  equal  supply  to  each  cylinder.  Exhaust  manifolds  are 
of  seamless  steel  tubing. 

The  cylinders  are  4^  bore  x  4^  stroke,  and  develop  60  to 
70  horse-power  at  1,100  revolutions  per  minute,  which  speed 
has  been  attained  with  an  8-foot  6-inch  propeller  having  a  pitch 
of  5  feet.  Without  radiator  or  propeller,  the  iron  jacketed  motor 
weighs  312  pounds,  and  copper  jacketed  weighs  290  pounds, 
the  latter  making  a  difference  of  22  pounds  in  the  weight. 

A  high  tension  Bosch  magneto  is  used  which  is  mounted  on 
a  pad  cast  on  the  top  of  the  crank-case  and  is  driven  from  a 
gear  meshing  with  the  cam  shaft  gear.  Connection  is  made 
from  the  magneto  to  plugs  placed  over  the  inlet  valves  in  the 
valve  caps. 

A  100  horse-power  aero  engine  of  the  "V"  type  is  shown  by 
Figs.  23-24-25,  which  is  built  by  the  All  British  Engine  Com- 
pany for  the  aeronautical  branch  of  the  English  War  Depart- 
ment. It  has  eight  cylinders  of  5  inch  bore,  by  4%  inch  stroke, 
and  develops  its  rated  horse-power  at  1,200  revolutions  per 
minute.  Data  from  "Aero,"  London. 

'  The  crankshaft,  which  is  of  three  per  cent  nickel  chrome  steel, 
having  an  ultimate  tensile  strength  of  157,000  Ibs.  per  sq.  in., 
is  of  distinctly  large  diameter,  and  is  carried  in  plain  bearings 


GAS,  OIL  AND  STEAM  ENGINES  111 


Fig.     23,     Longitudinal     Section     Through     A.     B.  *  C.     100     Horse-Power 
"V"    Motor. 


112 


GAS,  OIL  AND  STEAM  ENGINES 


lined  with  white  metal.  It  is  provided  with  four  throws,  each 
crank  pin  being  arranged  to  take  the  big  end  bearings  of  two 
connecting  rods  from  cylinders  on  opposite  sides  of  the  crank 
case.  There  is  a  bearing  between  each  throw,  and  in  order  to 
reduce  the  overall  length  of  the  engine  the  cylinders  are  stag- 
gered on  the  crank  case.  The  H  section  connecting  rods  are 
stamped  out  of  steel  having  a  tensile  strength  of  90,000  Ibs.  per 
sq.  in.,  and  for  the  purpose  of  lubrication  a  hole  is  drilled  from 
end  to  end  down  the  center  of  the  web.  As  mentioned  before, 


Fig.  24.     Valves  and  Valve  Motion  of  A.   B.  C.  Motor.     ("Aero,"  London.) 

the  cylinders  are  staggered,  and  there  is  no  overhanging  of 
the  big  end  bearings  at  the  point  of  attachment  to  the  con- 
necting rod.  The  bearings  themselves  are  lined  with  white 
metal.  The  small  end  bearings  are  provided  with  phosphor 
bronze  bushes,  and  the  piston  pin  is  of  steel  bored  out  hollow 
and  hardened. 

A  very  interesting  detail  of  the  engine  is  the  combination  of 
the  water  outlet  pipe  from  the  top  of  the  cylinder  with  the 
bearings  for  the  rocking  arms  (which  are  steel  stampings) 
actuating  the  valves.  This  is  shown  in  Fig.  25.  A  hollow  steel 
column  is  bolted  to  the  top  of  the  cylinder  and  protrudes  from 
the  water  jacket,  which  is  fastened  to  it  with  the  usual  shrunk 


GAS,  OIL  AND  STEAM  ENGINES 


113 


ring.  To  this  column  rs  attached  a  hollow  T  shaped  pipe  of 
phosphor  bronze,  the  column  of  the  T  piece  forming  the  out- 
let for  the  water.  On  one  arm  of  the  T  piece  the  exhaust 
rocker  takes  its  bearing  and  on  the  other  the  inlet  rocker. 
Each  T  piece  arm  is  connect  A  to  its  fellow  on  the  next  cylin- 
der by  means  of  rubber  pip  . 


Fig.    25.     End    Elevation    of   A.    B.    C.    Motor. 

A  small  bracket  projecting  from  the  T  piece  forms  a  saddle 
on  which  the  valve  spring  rests.  This  is  a  plain  semi-elliptical 
leaf  spring  which  works  both  valves.  It  is  slotted  at  each  end 
and  slightly  turned  up  so  as  to  engage  with  a  cotter  pin  passed 
through  a  slot  in  the  end  of  the  valve  stem. 

The  crank  case  is  of  rather  unusual  design,  being  absolutely 
circular  in  section  and  machined  all  over.  It  is  practically  a 
tube  with  flanged  portions  bolted  on  to  form  the  ends.  Having 
no  horizontal  joints,  it  is  strong  and  easily  kept  oil  tight.  Three 


114  GAS,  OIL  AND  STEAM  ENGINES 

radial  arms,  with  slight  webs  and  reinforced  with  steel  colums 
down  the  center,  support  each  bearing.  The  crank  case  is  car- 
ried by  four  feet,  which  are  arranged  to  accommodate  three 
different  widths  of  engine  bearer.  To  the  fore  end  of  the  crank 
case  is  bolted  a  long  conical  aluminum  nose  carrying  at  its  ex- 
tremity a  compound  push  and  pull  ball  bearing  6  in.  in  diameter, 
which  supports  an  extension  shaft  bolted  to  the  crankshaft  by 
means  of  a  flanged  coupling. 


Fig.  24-a.  "Sixteen"  Cylinder  Favata  Radial  Type  Aero  Motor,  Con- 
sisting of  Four  Groups  of  Two  Cylinders  Per  Group.  Cylinders  are 
of  the  Double  Acting  Type  and  are  Stationary. 

At  the  outer  end  of  this  extension  is  a  flange  to  which  the 
propeller  is  bolted,  but  the  arrangement  is  specially  devised  to 
make  quick  detachment  possible.  The  boss  of  the  propeller  has 
a  hollow  hub  and  is  plate  bolted  permanently  to  it  by  twelve 
bolts. 

The  direct  nose  is  interchangeable  with  a  speed  reduction 
gear  so  that  the  propeller  can  be  driven  at  a  lower  speed  than 
the  engine.  Fitting  this  gear  nose  raises  the  center  line  of  the 
propeller-shaft  some  5%  in.  The  gears  are  carried  on  sub- 


GAS,  OIL  AND  STEAM  ENGINES  115 

stantial  ball  bearings,  plain  bearings  being  used  also  in  such  a 
way  that  they  take  up  the  load  if  the  ball  bearings  through 
any  cause  should  fail.  The  reduction  is  by  means  of  silent  chains. 
The  arrangement  of  the  gear  wheels  is  plain  from  the  drawing, 
and  it  will  be  noticed  that  there  is  no  intermediate  wheel  be- 
tween the  crankshaft  pinion  and  the  camshaft  wheel,  which  are 
of  steel  and  phosphor  bronze  respectively.  A  separate  gear 
wheel  is  provided  on  the  camshaft  for  driving  the  magneto. 
The  water  and  oil  pumps  are  carried  low  down  outside  the 
crank  case,  and  are  driven  by  intermediate  wheels  at  double 
the  engine  speed.  The  shafts  are  joined  together  through 
Oldham  couplings,  so  that  it  is  possible  to  remove  the  pumps 
separately.  Both  these  pumps  are  of  the  gear  type. 

The  camshaft  is  made  in  one  piece  with  the  cams,  and  is 
hardened,  being  drilled  out  for  lightness.  It  is  enclosed  in  a 
casing  of  steel  tube,  which  .is  practically  separate  from  the 
crank  case,  being  attached  thereto  at  one  end  by  the  timing 
gear  case  and  at  the  other  by  a  saddle.  The  camshaft  is  car- 
ried in  six  bearings.  An  interesting  point  is  the  fact  that  the 
gear  wheels  are  bolted  to  flanges  on  the  shafts  instead  of  be- 
ing attached  by  keys.  Carried  in  the  tube  directly  above  the 
camshaft  is  a  second  shaft  forming  the  fulcrum  of  the  rocking 
arms  for  the  cam  rollers.  A  very  interesting  point  is  the  pro- 
vision of  an  arrangement  for  lifting  the  exhaust  valves.  The 
little  rocking  arms  carrying  the  rollers  which  bear  upon  the 
cams  are  provided  with  webs,  parallel  with  the  camshaft  and 
between  it  and  the  shaft  carrying  the  rockers  is  a  third  shaft,' 
the  sides  of  which  normally  just  clear  the  webs  of  the  rock- 
ing arms  on  either  side.  This  shaft  is  provided  with  wedge 
shape  pieces  along  it,  so  that  by  sliding  it  along  the  wedges 
lift  the  rocking  arms  clear  of  the  cams,  and  thus,  through  the 
tappet  rods  and  rockers,  the  valves  themselves  are  opened. 

Not  the  least  interesting  particular  of  this  engine  is  the 
thorough  way  in  which  the  lubrication  is  carried  out.  Four 
of  the  bolts  which  attach  the  caps  of  the  main  bearings  are 
prolonged  through  the  bottom  of  the  crank  case,  and  serve  to 
carry  a  detachable  oil  sump  which  holds  sufficient  oil  for  a  run  of 
six  hours.  As  already  mentioned,  the  oil  pump  is  driven  at  twice 
the  engine  speed,  and  maintains  a  pressure  of  something  like  110 
pounds  per  square  inch.  It  delivers  directly  into  a  straight  steel 
tube  placed  along  the  bottom  of  the  crank  case,  and  from 
this  tube  a  vertical  tubular  connection  is  taken  to  each  of  the 
caps  of  the  main  bearings.  The  crankshaft  and  crank  pins  are 


116  GAS,  OIL  AND  STEAM  ENGINES 


Fig.  26.     Mesta  Engines  on  Test  Floor. 


GAS,  OIL  AND  STEAM  ENGINES  117 

hollow,  and,  as  in  the  previous  engine,  in  the  hollow  portions 
tubes  of  a  slightly  smaller  diameter  are  placed,  the  tubes  being 
expanded  over  at  the  ends,  so  that  closed  annular  spaces  are 
formed  which  are  used  as  lubrication  leads.  The  lubricating 
oil  passes  through  the  main  bearings  into  these  annular  spaces 
in  the  shafts,  from  them  to  the  annular  spaces  in  the  crank 
pins,  and  so  to  the  big-end  bearings.  From  the  big-end  bear- 
ings it  travels  up  the  connecting  rods  to  the  gudgeon  pins. 
It  is  interesting  to  note  at  this  point  that  the  connecting  rods 
work  in  slots  in  tfce  crank  case  which  just  allow  sufficient  clear- 
ance for  their  travel,  in  order  to  prevent  the  flooding  of  oil 
into  the  cylinders.  A  steel-lined  oil  lead  is  taken  up  to  the 
saddle  which  supports  the  tubular  camshaft  casing  at  the  pro- 
peller end  of  the  crank  case.  The  bearings  carrying  the  cam- 
shaft are  cut  away  at  their  lower  edges  clear  of  the  tube  so 
that  the  oil  can  flow  along  the  full  length  of  the  casing,  the 
level  being  sufficient  to  allow  the  cams  to  dip.  Precautions  are 
taken  to  keep  oil  from  flowing  out  of  the  bearings,  and  the 
casing  over  the  gears  is  specially  arranged  to  prevent  the  oil 
from  flooding  below. 

(48)  Mesta  Gas  Engines. 

The  Mesta  four  stroke  cycle,  double  acting  gas  engine,  built 
by  the  Mesta  Machine  Co.,  Pittsburgh,  is  an  excellent  example 
of  American  big  engine  practice.  Mesta  engines  are  built  in 
sizes  from  400  horse-power  up  to  the  largest  used,  and  is  built 
either  in  tandem  or  twin  tandem  units.  While  the  engine  does 
not  differ  widely  in  either  principle  or  construction  from  en- 
gines of  the  same  size  it  has  several  features  worthy  of  note 
that  are  not  found  on  other  engines. 

Up  to  the  medium  sizes,  the  cylinders  are  cast  in  one  piece, 
the  largest  cylinders  being  made  in  two  parts  of  cast  steel  with 
air  furnace  iron  bushings.  The  central  part  of  the  cylinder  is 
open  as  will  be  seen  from  the  cuts,  and  is  covered  with  a 
cast  iron  split  band  bolted  at  the  center  line.  The  valve  cham- 
bers are  located  directly  opposite  one  another  on  a  vertical 
center  line,  the  inlet  valve  being  at  the  top  and  the  exhaust 
valve  at  the  bottom.  This  arrangement  gives  a  better  dis- 
tribution of  the  mixture,  increases  the  output  with  given  size 
of  cylinder  and  equalizes  the  stresses  occasioned  by  the  ex- 
plosions. As  the  e"ngine  is  double  acting  in  all  cases  there  is 
one  inlet  and  one  exhaust  at  each  end  of  the  cylinder. 

Both  the  inlet  valve  and  the  corresponding  exhaust  valve  on 


118 


GAS,  OIL  AND  STEAM  ENGINES 


each  end  of  the  cylinder  are  operated  by  a  single  eccentric  on 
the  horizontal  lay-shaft  shown  running  below  and  parallel  to 
the  cylinders.  The  regulating  valves  which  are  controlled  by 
the  action  of  the  governor  are  perfectly  balanced  against  the 
pressure  in  the  cylinder  which  results  in  a  very  small  resist- 
ance to  tHe  governor  action,  therefore  no  oil  relay  nor  similar 
complications  are  required.  Any  of  these  valves  are  easily  re- 
moved for  clearing,  a  point  of  great  importance  when  running 
on  a  gas  that  is  laden  with  tar  or  other  impurities. 


Fig.   27.     End  View   of   Mesta   Engine. 

The  chrome-vanadium  piston  rod  carries  the  pistons  float- 
ing free  from  the  cylinder  walls  reducing  the  wear  on  the  bore, 
while  the  piston  rings  maintain  a  gas  tight  contact  with  the 
cylinder  walls.  Each  piston  rod  is  made  in  two  halves,  the 
joint  between  the  sections  being  made  between  the  cylinders  at 
which  point  the  rods  are  supported  by  an  .intermediate  cross- 
head  and  guide.  Both  parts  of  the  rod  are  interchangeable. 
The  pistons  are  made  in  one  casting.  As  will  be  seen  from 


GAS,  OIL  AND  STEAM  ENGINES  119 

the  accompanying  cuts  the  front  end  of  the  piston  rod  is  car- 
ried by  a  cross-head  which  relieves  the  pressure  on  the  piston 
and  packing  glands. 

Speed  regulation  is  performed  by  the  governor  by  control- 
ling both  the  quantity  and  the  quality  of  the  mixture.  Inde- 
pendent valves  in  the  gas  and  air  passages  are  actuated  by  the 
governor  according  to  changes  in  the  load.  This  method  of 
control  combines  all  of  the  good  features  of  quantity  and 
quality  regulation. 

Make  and  break  ignition  is  used,  with  the  igniter  trip  gear 
so  designed  as  to  allow  all  of  the  igniters  to  be  timed  from 
one  lever,  or  adjusted  independently  as  the  case  may  require. 
Each  combustion  chamber  is  supplied  with  two  igniters,  one 
at  the  top  and  on  at  the  bottom,  which  insures  regular  and 
rapid  combustion  and  therefore  gives  a  maximum  of  efficiency 
and  reliability. 

Compressed  air  is  introduced  into  the  cylinders  for  starting 
at  a  period  corresponding  to  the  power  stroke  in  normal  opera- 
tion. This  is  accomplished  by  cam  operated  poppet  valves 
located  in  the  air  main  a/id  check  valves  in  the  cylinders.  By 
this  system  the  engine  can  be  started  and  put  on  full  load  in 
less  than  one  minute. 

(49)  Knight  Sliding  Sleeve  Motor. 

The  Knight  motor  was  the  first  four  stroke  cycle  automobile 
motor  to  employ  an  annular  slide  valve  in  place  of  the  usual 
poppet  valve.  Its  success  has  led  to  the  development  of  sev- 
eral other  motors  of  a  similar  type  which  follow  the  construc- 
tion of  the  original  engine  more  or  less  closely.  Being  free 
from  the  slap  bang  of  eight  to  twelve  cam  actuated  poppet 
valves  which  hammer  on  their  seats  at  the  rate  of  a  thousand 
blows  per  minute,  the  Knight  motor  is  free  from  noise  and 
vibration.  Instead  of  the  jumping  of  a  number  of  small  parts, 
there  is  only  the  slow  sliding  of  the  sleeves  over  well  lubricated 
surfaces.  They  make  no  noise  because  they  strike  nothing  and 
can  cause  no  vibration  because  they  are  a  perfect  sliding  fit 
in  their  respective  cylinders. 

Besides  insuring  noiseless  operation,  the  valves  increase  the 
output,  efficiency  and  flexibility  of  the  motor  for  they  are  posi- 
tively driven  and  are  not  affected  in  timing  by  fluctuations  in 
the  speed.  The  wear  of  the  reciprocating  increases  the  effi- 
ciency of  the  sleeve  instead  of  destroying  it.  With  poppet 
valves  at  high  speeds,  the  valves  do  not  seat  properly  irr  rela- 


120 


GAS,  OIL  AND  STEAM  ENGINES 


tion  to  the  crank  position  owing  to  the  inertia  of  the  valves 
and  to  the  gradual  weakening  of  the  valve  springs  which  delays 
the  closing  of  the  valves..  Carbon  also  gets  on  the  seats  of 
the  poppet  valves  and  prevents  proper  closure.  These  faults 
cannot  exist  with  sliding  sleeves  when  they  are  once  set  right 


Fig.  28.  Section  Through  Knight  Motor  Showing  the  Sleeves,  Eccen- 
trics, and  Automatic  Adjustment  for  Lubrication.  Inlet  is  at  the 
Right,  Exhaust  at  the  Left. 

as  they  are  positively  driven  through  a  crank  and  connecting 
rod. 

At  high  engine  speeds  the  velocity  of  the  exhaust  and  inlet 
gases  is  very  high  in  the  poppet  valve  type  due  to  the  many 
restrictions  and  turns  in  the  passages  which  causes  back  pres- 


GAS,  OIL  AND  STEAM  ENGINES 


121 


sure  and  a  considerable  loss  of  power.  With  the  sliding  sleeve 
type  an  ideal  form  of  combustion  chamber  is  possible  and  the 
passages  to  and  from  the  chamber  are  short  and  direct.  Very 
large  port  areas  with  a  low  gas  velocity  are  also  possible.  The 
sleeves  are  more  effectively  cooled  than  the  poppet  type,  being 
in  direct  contact  with  the  water  cooled  walls  for  their  entire 


INLET  OPENS 


INLET  CLOSES 


INNER  SLEEVE  UP 
OUTER  SLEEVE  IS 
MOVING  DOWN 


BOTH  SLEEVES 
ARE  MOVING  UP 
IN  REGISTER. 


BOTH  SLEEVES 
ARE  MOVING 
INNETR  CLOSEIS. 


—29— 


—30— 


Figs.    28-29-30.     Showing   Sleeve    Positions   on   the    Inlet    Stroke.      (Knight 

Motor.) 

length.  Because  of  the  large  port  areas,  the  cylinders  receive 
a  full  charge  of  mixture,  and  as  a  result  the  engine  accelerates 
and  gets  under  way  with  remarkable  ease. 

The   arrangement   of   the    slide   valves,   or   sleeves,   is   shown 
by  Fig.  28,  which  also  gives  an  idea  of  the  cylinder  form,  and 


122 


GAS,  OIL  AND  STEAM  ENGINES 


the  location  of  the  piston.  Fitting  the  engine  cylinder  closely, 
one  within  the  other,  are  the  two  sliding  valve  sleeves,  and 
within  the  inner  sleeve  slides  the  power  piston. 

Each  sleeve  has  two  slots  cut  in  it,  one  on  each  side,  which 
form  an  outlet  and  inlet  for  the  exhaust  and  inlet  gases  respect- 
ively. When  the  slots  on  the  intake  side  of  both  the  outer  and 


OPEN 


EXHAUST  CLOSES 


BOTH  ARE  MOV- 
ING DOWN;  BOTH 
BLOTS  ENTERING 


BOTH  ARE  MOV- 
ING DOWN  IN 


INNER  SLEEVE  UP. 
OUTER  SLEEVE  IQ 
MOVIN©  DOWN. 


—31—  —32—  —33— 

Figs.    31-32-33.      Showing    Sleeve    Positions    on    the    Exhaust    Stroke. 

the  inner  sleeves  register,  or  come  opposite  to  one  another, 
and  also  opposite  to  the  intake  pipe,  a  charge  of  gas  is  drawn 
into  the  cylinder.  After  the  explosion  has  taken  place,  the 
sliding  motion  of  the  sleeves  brings  the  other  two  openings,  on 
the  exhaust  side,  opposite  to  one  another,  and  opposite  the 


GAS,  OIL  AND  STEAM  ENGINES  123 

exhaust  pipe,  which  allows  the  burnt  gas  to  escape  to  the  at- 
mosphere through  the  exhaust  manifold. 

The  sleeves  are  driven  from  cranks  on  the  half-time  shaft 
shown  at  the  side  of  each  cut,  through  the  small  connecting 
rods,  which  gives  them  a  reciprocating  motion.  Like  the  cam 
shaft  on  a  poppet  valve  motor,  the  lay  shaft  runs  at  half  the 
crank  shaft  speed,  since  the  engine  is  of  the  four-stroke  cycle 
type.  The  lower  ends  of  the  sleeves,,  to  which  the  connecting 
rods  are  fastened,  are  made  thicker  than  the  portion  within 
the  cylinder,  and  are  heavily  ribbed  for  strength  in  the  over- 
hang. 

The  sleeves  are  of  the  same  composition  of  cast  iron  as  the 
cylinder  and  are  provided  with  oil  grooves  cut  in  their  outer 
surfaces  for  gas  packing,  and  the  distribution  of  oil.  Leakage 
between  the  inner  sleeve,  and  the  cylinder  head  is  prevented 
by  a  packing  ring,  or  "junk"  ring  that  is  fastened  to  the  bot- 
tom of  the  inwardly  projecting  cylinder  head.  The  junk  ring 
not  only  prevents  the  leakage  of  gas  during  the  explosion,  but 
it  also  serves  another  purpose. 

The  exhaust  ports  or  slots  in  the  inner  sleeve  are  above  the 
junk  ring  during  the  explosion,  in  which  position  they  are  pro- 
tected from  contact  with  the  burning  gas.  The  life  of  valves 
is  greatly  increased  by  this  protection.  It  will  be  noted  that 
the  entire  surface  of  the  sleeves  is  in  contact  with  water  jacketed 
surfaces,  making  perfect  lubrication  and  smooth  working  pos- 
sible. The  two  spark  plugs  for  the  dual  ignition  system  are 
shown  in  the  depressed  cylinder  head. 

Complete  water  jacketing  encircles  the  cylinders,  cylinder 
heads,  the  circulation  area  enclosing  the  plugs  and  the  gas 
passages  so  that  a  uniform  heat  is  maintained  the  entire  length 
of  the  piston  travel. 

The  half-time  shaft,  the  magneto,  and  the  water  pump  are 
driven  by  a  silent  chain  from  the  crank  case;  this  drive  being 
found  superior  to  the  gears  commonly  used  for  this -class  of 
work.  The  cranks  on  the  half-time  shaft  are  made  in  one  in- 
tegral piece  with  the  shaft. 

Although  the  piston  on  the-  Stoddard-Dayton  Knight  motor 
has  a  stroke  of  5l/2  inches,  it  is  scarcely  as  much  as  this  con- 
sidered as  friction  producing  travel,  because  the  inner  sleeve  in 
which  it  rests  moves  down  in  the  same  direction  l^j  inches. 

This  distribution  of  the  working  stroke  to  two  surfaces 
reduces  the  wear  on  the  side  of  the  sleeve  caused  by  the  angu- 
larity or  thrust  of  the  main  connecting  rod.  On  the  compres- 


124  GAS,  OIL  AND  STEAM  ENGINES 

sion  stroke,  both  outer  and  inner  sleeves  go  up  in  the  same 
direction  as  the  piston,  the  inner  sleeve  moving  the  faster.  On 
the  exhaust  stroke  and  suction  stroke  the  sleeves  move  in  a 
direction  opposite  to  the  direction  of  the  piston,  but  on  these 
strokes  there  is  very  little  work  performed  by  the  piston  and 
consequently  little  thrust  is  produced  on  the  sleeves  and  walls 
of  the  cylinder. 

It  is  a  valuable  feature  to  have  the  sleeves  descend  with  the 
piston  on  the  working  stroke  because  this  is  the  stroke  in 
which  the  piston  has  the  greatest  amount  of  side  thrust. 

The  up  and  down  movement  of  the  sleeves  is  very  little  com- 
pared with  that  of  the  piston.  A  stroke  of  Sl/2  inches  gives  a 
piston  speed  of  916  feet  per  minute  at  a  speed  of  1,000  revolu- 
tions per  minute.  The  stroke  of  the  sleeves  is  1^  inches  and 
its  speed  is  but  93.7  feet  per  minute,  or  a  little  more  than 
one-tenth  that  of  the  piston.  This  fact  makes  the  problem  of 
lubrication  a  feasible  one,  the  slow-movement  of  the  sleeves 
distributing  the  oil  thoroughly  between  them  as  well  as  be- 
tween the  outer  sleeves  and  the  cylinder  walls. 

The  action  of  the  valves,  and  their  position  at  different  points 
in  the  cycle,  is  shown  in  diagrammatic  form  by  Figs.  28-29-30- 
31-32-33,  the  particular  event  to  which  each  diagram  refers 
being  marked  at  the  foot  of  the  cuts.  The  direction  of  the 
sleeve  movement  is  indicated  by  the  arrows  at  the  bottom 
of  the  sleeves.  Particular  attention  should  be  paid  to  the  posi- 
tion of  the  slots  in  the  sleeves. 

The  first  three  diagrams  show  the  position  of  the  inlet  shots 
that  govern  the  admission  of  the  combustible  gas  from  the 
carburetor.  Fig.  28  shows  the  slots  coming  together  to  form 
an  opening  in  the  inlet  port  as  the  lower  edge  of  the  outer 
sleeve  separates  from  the  upper  edge  of  the  inner  sleeve.  The 
outer  sleeve  is  now  moving  rapidly  downward  while  the  inner 
sleeve  is  slowly  rising,  and  as  their  motion  is  opposite  the 
opening  'is  quickly  formed.  Fig.  29  shows  the  full  opening 
with  the  slots  in  register. 

When  closing  (Fig.  30)  the  outer  sleeve  is  nearly  stationary 
while  the  inner  sleeve  is  rising  ra'pidly.  When  the  inner  sleeve 
port  is  covered  by  the  lower  edge  of  the  junk  ring,  the  valve 
opening  is  closed,  the  slot  in  the  outer  sleeve  remaining  oppo- 
site the  inlet  opening. 

The  exhaust  port  opens  (Fig.  31)  when  the  lower  edge  of 
the  slot  in  the  inner  sleeve  leaves  the  junk  ring  in  the  cyl- 
inder head,  the  sleeve  moving  rapidly  downward  at  the  mo- 


GAS,  OIL  AND  STEAM  ENGINES  125 

ment  of  opening.  To  obtain  a  rapid  opening  of  the  exhaust, 
the  ports  are  arranged  so  that  the  inner  sleeve  is  just  about 
to  reach  its  maximum  speed  at  the  time  of  opening. 

The  outer  sleeve  closes  the  port  (Fig.  33),  closure  starting 
when  the  upper  edge  of  the  outer  sleeve  coincides  with  the 
lower  edge  of  the  cylinder  wall  port.  At  this  time  the  outer 
sleeve  is  traveling  downward  at  maximum  speed,  so  that  the 
closing  of  the  exhaust  is  as  rapid  as  the  opening. 

The  lubrication  of  the  Knight  motor  is  accomplished  by  what 
is  known  as  the  movable  dam  system,  which  overcomes  the 
tendency  of  the  motor  to  over-lubricate.  A  movable  trough  is 
placed  under  each  connecting  rod,  in  the  crank  case,  that  is 
connected  to  the  carburetor  throttle  lever  in  such  a  way  that 
the  opening  and  closing  of  the  throttle  raises  and  lowers  the 
troughs. 

When  the  throttle  is  opened,  raising  the  troughs,  the  points 
on  the  ends  of  the  connecting  rods  dip  deeper  into  the  oil  which 
creates  a  splashing  of  oil  on  the  lower  ends  of  the  sliding 
sleeves.  In  this  way  the  oil  is  fed  to  the  engine  in  direct  pro- 
portion to  the  load  and  the  heat  produced  in  the  cylinder.  When 
the  motor  is  throttled  down,  the  points  barely  dip  into  the  oil. 

An  excess  of  oil  is  fed  to  the  troughs  by  an  oil  pump,  which 
keeps  them  constantly  overflowing.  The  overflow  is  caught  in 
the  pumps  located  in  the  crank  case,  and  returned  to  the  circu- 
lation so  that  it  is  used  over  and  over  again. 

Claims  of  great  efficiency  are  made  for  this  system,  there  hav- 
ing been  many  tests  made  showing  750  miles  per  gallon  of  oil, 
while  even  as  high  as  1,200  miles  per  gallon  has  been  made  un- 
der favorable  conditions. 

The  oil  pump  is  contained  in  the  crank  case,  and  is  of  the 
gear  type,  insuring  positive  action.  The  pump  also  acts  as  a 
distributer,  a  slot  being  cut  in  one  of  the  gears  which  register 
successively  with  each  of  the  six  oil  leads.  In  this  way  it  is 
possible  to  obtain  the  full  pump  pressure  in  each  lead  should 
they  become  obstructed  in  any  way. 

In  the  upper  half  of  the  crank  case  are  cored  passageways 
through  which  the  air  passes  before  reaching  the  carburetor. 
These  passages  not  only  eliminate  ^he  rushing  sound  of  the 
intake  air,  but  also  form  an  efficient  method  of  warming  the 
air  supplied  to  the  carburetor  and  cooling  the  crank-case.  It 
is  possible  to  furnish  warm  air  after  the  engine  has  been  idle 
for  several  hours,  as  the  oil  in  the  crank  case  remains  warm 
longer  than  any  other  part  of  the  engine. 


126 


GAS,  OIL  AND  STEAM  ENGINES 


(50)  Reeves  Slide  Sleeve  Valve. 

A  simple  and  compact  form  of  slide  sleeve  valve  gear  has 
been  developed  in  England  that  is  of  more  than  passing  interest. 
It  permits  of  a  maximum  area  for  both  the  inlet  and  exhaust 
gases  which  of  course  keeps  the  velocity  and  back  pressure  at 
a  minimum  for  a  given  valve  lift.  The  small  lift  also  insures 
noiseless  operation  and  a  small  amount  of  wear.  The  sleeve 


Fig.    34.     Reeves    Slide    Valve    Gear. 

is  balanced  at  the  end  of  the  working  stroke.  The  combustion 
chamber  is  nearly  hemispherical  in  shape  which  reduces  the 
heat  loss  to  the  walls. 

Referring  to  the  section  of  the  end  of  cylinder  given  in  the 
diagram,  (34)  A  is  an  .open-ended  water-jacketed  cylinder  in 
which  the  piston  B  works.  At  the  upper  end  of  the  cylinder  is 
attached  a  ring  C  forming  an  extension  of  the  stationary  cylin- 
drical head  D  carrying  the  sparking  plug.  At  the  lower  end 
of  the  head  D  is  provided  a  seating  E  for  the  sliding  cylindrical 


GAS,  OIL  AND  STEAM  ENGINES  127 

inlet  valve  F,  which  takes  its  bearing  around  the  circular  head. 
This  inlet  valve  is  provided  with  expanding  rings  G  to  keep 
it  gas-tight.  Surrounding  the  inlet  valve  F  is  a  second  cylindri- 
cal exhaust  valve  H,  which  is  provided  with  an  angular  seating 
at  J.  The  outer  circumference  of  the  cylindrical  exhaust  valve 
H  bears  against  the  walls  of  the  cylinder. 

Cast  in  the  cylinder  is  an  annular  space  K  communicating 
with  a  passage  L  for  the  admission  of  the  inlet  gases.  These 
pass  through  suitable  ports  cut  in  the  sides  of  the  exhaust 
valve  H  and  the  inlet  valve  F,  so  that  they  are  free  to  pass 
through  the  space  made  when  the  inlet  valve  F  is  lowered  from 
its  seat.  A  similar  type  of  annular  space  M  is  cast  in  the 
cylinder  in  connection  with  an  opening  O  for  the  passage  of 
the  exhaust  gas  when  the  cylindrical  valve  H  is  raised  from  its 
seating  at  J. 

The  cylinder  head  is  not  water  jacketed  as  the  builder  states 
that  the  continual  passage  of  the  intake  gases  keeps  it  reason- 
ably cool.  The  exhaust  passages  are  thoroughly  water  cooled. 

(51)  Argyll  Single  Sleeve  Motor. 

The  Argyll  sliding  sleeve  automobile  motor  is  unique  in  the 
fact  that  only  one  sleeve  is  used  to  control  both  the  inlet  and 
exhaust  gases  instead  of  the  two  sleeves  commonly  used  on 
the  Knight  motor.  This  sleeve,  instead  of  having  either  a 
purely  vertical  or  horizontal  motion,  has  a  peculiar  combina- 
tion of  the  two,  that  is  to  say,  it  moves  a  certain  amount  in 
rotation  within  the  cylinder,  and  an  equal  amount  vertically, 
the  combined  motion  constituting  an  ellipse.  The  external  ap- 
pearance of  the  engine  is  shown  by  Fig.  35,  which  will  give  an 
idea  of  the  general  arrangement  of  the  cylinders,  ports  and 
piping. 

In  Fig.  36,  is  shown  the  successive  movements  and  events 
determined  by  the  sleeve,  and  the  method  of  opening  and  clos- 
ing the  inlet  and  exhaust  ports  by  the  elliptical  movement  of 
the  sleeve.  The  shaded  ports  are  one  of  the  inlet  and  one 
of  the  outlet  ports,  respectively,  which  are  cast  in  the  cylinder 
wall,  and  are  afterwards  machined  true.  The  dotted  port,  which 
changes  its  position  in  each  diagram,  is  one  of  the  ports  in  the 
moving  sleeve,  its  position  in  each  of  the  figures  is  marked 
by  the  event  that  is  occurring  in  the  "cylinder  at  that  time. 

In  diagram  1,  the  shaded  port  to  the  right  is  the  exhaust 
port,  and  the  shaded  port  to  the  left,  the  inlet,  this  relative 
arrangement  being  true,  of  course,  in  each  of  the  succeeding 


128 


GAS,  OIL  AND  STEAM  ENGINES 


diagrams.  It  will  be  noted,  that  in  the  position  shown,  in  the 
exhaust  stroke  (beginning  of  stroke),  the  sleeve  port  has  just 
started  on  its  downward  stroke,  moving  also  a  trifle  to  the 
right  as  it  progresses.  Its  progress  to  the  right  may  be  more 
clearly  seen  by  consulting  diagram  2,  for  the  movement. 

By  consulting  the  other  five  figures  it  will  be  seen  that  the 
dotted  port,  in  its  relation  to  the  shaded  ports,  first  moves  out 
to  the  right,  and  then  reverses,  moving  to  the  left,  and  this 
combined  wih  the  up  and  down  movement  constitutes  an  ellip- 


Fig.    35.     Elevation    of    Argyll    Single    Sleeve    Motor    from    The    Motor, 

London. 

tical  path.  In  diagram  6  the  exhaust  is  closed,  and  the  inlet 
port  has  just  begun  to  open,  the  dotted  port  now  starting  to 
move  out  to  the  left,  and  to  rise. 

In  diagram  10,  the  inlet  is  nearly  closed,  the  sleeve  port  pass- 
ing away  from  the  cylinder  ports  to  the  water  jacketed  portion 
of  the  cylinder  above. 

This  series  of  diagrams  shows  the  operation  of  the  dupli- 
cated port  of  the  sleeve  (which  port  is  the  one  shown  dotted) 
in  relation  with  one  of  the  inlet  ports  and  one  of  the  exhaust 
ports  in  the  cylinder  wall,  the  latter  ports  being  marked  re- 
spectively I  and  E.  The  elliptical  movement  referred  to  in  the 
text  can  be  traced  by  following  the  different  positions  of  the 


GAS,  OIL  AND  STEAM  ENGINES 


129 


dotted  port  in  the  sleeve.  In  the  top  row  of  diagrams  it  is 
seen  to  come  downwards  and  also  to  move  over  to  the  left, 
whilst  in  the  lower  set  it  rises — bearing  still  to  the  left — until, 
after  Fig.  10,  it  goes  higher  up  for  the  compression  and  ex- 
plosion strokes,  during  which  it  bears  over  to  the  right  and 
comes  down  again  ready  to  commence  once  more  the  cycle, 
as  in  Fig.  1.  The  other  ports  in  the  cylinder  wall  are  the  same 


CXMAUfcT  BCCINS  TO  ClO<>£ 


inter..          \oecmsTo  CLOSE 


r,c.  a 


X'IN1XT    MBAIU.Y     CLOSED 
/ I 


FlC.9. 


PlC.  10 


Fig.    36.     Valve    Motion    Diagram    of    Argyll    Motor    Showing    the    Valve 
Positions    at    Different    Parts    of    the    Working    Stroke. 

as  those  shown,  and  the  other  ports  in  the  sleeve  are  akin  in 
shape  to  half  of  the  dotted  port,  but  they  are  without  the  little 
tongue  cut  in  the  base  of  this  double  purpose  port.  This  little 
tongue  in  the  duplicated  port  is  designed  to  give  as  much  lead 
to  the  exhaust  opening  as  possible,  without  interfering  with  the 
correct  timing  of  the  inlet  port.  The  way  in  which  it  just  misses 
interfering  with  the  closing  of  the  inlet  port  is  seen  in  Fig.  10. 
We  are  indebted  to  "The  Motor"  for  these  cuts. 


130  GAS,  OIL  AND  STEAM  ENGINES 

(53)  Sturtevant  Aeronautical  Motor. 

The  cylinders  of  the  Sturtevant  aeronautical  motor  are  of 
the  "L"  type  and  are  cast  separately  with  the  cylinder  barrel 
and  water  jacket  in  one  integral  casting.  A  special  iron  is 
used  for  these  castings  that  has  an  ultimate  tensile  strength  of 
40,000  pounds  per  square  inch.  The  valves  which  are  easily 
accessible  through  valve  covers,  are  operated  directly  from  the 
cam  shaft  without  valve  rockers.  A  hollow  cam  shaft  is  used 
with  integral  cams  to  insure  a  maximum  of  strength  with  a 
minimum  of  weight,  and  bearings  are  placed  between  each  set 


Fig.   41.     Six   Cylinder   Sturtevant   Aero   Motor. 

of  cams.     A  bronze  gear  fitted  on  the  cam  shaft  meshes  with 
a  gear  on  the  crank  shaft  without  intermediate  idlers. 

Like  the  cam  shaft,  the  crank  is  bored  out  from  end  to  end 
with  a  propeller  flange  applied  on  a  taper  at  one  end  of  the 
shaft.  A  bearing  is  provided  between  each  throw  with  an  addi- 
tional thrust  bearing  at  the  forward  end  of  the  shaft  which 
may  be  arranged  to  take  either  the  thrust  or  the  pull  of  the  pro- 
peller. Lubricating  oil  is  applied  to  all  the  bearings  under  a 
pressure  of  twenty  pounds  per  square  inch,  this  pressure  being 
maintained  by  a  gear  pump  attached  directly  to  the  end  of  the 
cam  shaft.  The  oil  is  transferred  from  the  pump  to  the  bearings 
through  passages  cast  in  the  base,  no  piping  being  used>  Oil 
enters  the  hollow  crank  shaft  at  the  main  bearings  and  is  con- 


GAS,  OIL  AND  STEAM  ENGINES 


131 


ducted  through  the  arms  to  the  connecting  rod  bearings.  The 
oil  flying  from  the  crank  shaft  falls  into  the  oil  sump  at  the 
bottom  of  the  case  where  it  is  cooled  before  being  used  again. 
A  second  gear  pump  in  tandem  with  the  first  takes  the  oil  from 
the  sump  and  forces  it  through  a  filter  into  the  tank. 


This  system  enables  the  use  of  a  more  efficient  filter  than 
with  the  suction  type  and  eliminates  any  danger  of  its  becoming 
clogged  and  stopping  the  oil  supply,  since,  in  the  event  of  such 
an  occurrence  the  pump  would  furnish  sufficient  pressure  to 


132  GAS,  OIL  AND  STEAM  ENGINES 

burst  the  filter.  However,  the  filter  is  particularly  accessible 
and  may  be  instantly  removed  for  cleaning  without  disturbing 
the  oil.  The  tank  regularly  fitted  to  the  motor  holds  sufficient 
oil  for  three  hours'  use.  If  the  engine  is  required  to  operate  for 
a  longer  time  without  opportunity  for  replenishing  the  oil  sup- 
ply, a  larger  tank  can  be  used.  As  no  oil  is  allowed  to  accu- 
mulate in  the  base  with  this  system  of  lubrication,  the  motor 
can  be  operated  continuously  at  an  angle. 

Water  circulation  is  maintained  by  a  centrifugal  pump  of 
large  capacity,  the  impeller  of  which  is  mounted  directly  on  an 
extension  of  the  crank  shaft,  eliminating  the  usual  bearings  and 
its  grease  cup. 

The  ignition  is  provided  by  a  high-tension  Mea  magneto,  its 
special  construction  permitting  the  motor  to  be  started  under 
a  retarded  spark  avoiding  the  danger  of  back  kick  from  the 
propeller. 

The  cylinder  and  all  exposed  parts  are  rendered  absolutely 
weather-proof  by  means  of  a  heavy  coat  of  nickel  plating. 

(54)  The  Rotating  Cylinder  Motor. 

While  it  is  the  common  belief  that  the  rotary  cylinder  gaso- 
line motor  is  of  French  origin  it  may  safely  be  said  that  this 
type  of  motor  was  in  actual  use  in  America  for  several  years 
before  it  even  reached  the  experimental  stage  in  Europe.  The 
Adams-Farwell  Company  of  Dubuque,  Iowa,  were  driving  auto- 
mobiles successfully  with  a  rotary  cylinder  motor  before  Or- 
ville  Wright  flew  at  Fort  Meyer,  Va.  Although  the  original 
Farwell  motor  more  than  proved  its  right  to  existence  by  faith- 
ful service  under  the  most  exacting  conditions,  the  motor  never 
received  the  consideration  that  it  deserved,  probably  because 
of  its  great  divergence  from  what  is  known  as  "accepted  prac- 
tice." 

In  Europe  no  such  prejudice  existed,  and  consequently  the 
type  made  rapid  strides,  although,  to  the  writer's  belief,  the 
European  model  is  inferior  in  many  ways  to  the  original  Ameri- 
can type.  The  fact  that  this  type  of  motor  holds  practically 
all  of  the  world's  aviati9n  records  speaks  for  its  practicability 
in  spite  of  its  unusual  construction. 

With  the  rotary  motor,  the  cylinders  and  crank  case  revolve 
about  a  stationary  crank  shaft,  the  latter  part  not  only  serv- 
ing as  a  point  of  reaction  of  the  cylinders  but  as  a  support  and 
intake  pipe  as  well.  Since  the  crank  throw  remains  stationary, 
the  cylinders  and  pistons  revolve  about  two  different  centers, 


GAS,  OIL  AND  STEAM  ENGINES  133 

the  cylinders  revolving  about  the  crank  case  and  the  pistons 
and  connecting  rods  about  the  crank  pin.  Since  the  pistons, 
cylinders,  and  connecting  rods  must  necessarily  revolve  to- 
gether, as  one  unit,  there  is  absolutely  no  reciprocating  mo- 
tion in  regard  to  the  crank  shaft  except  for  a  very  slight  move- 
ment due  to  the  difference  in  angularity  of  the  connecting  rods. 
The  motion  of  all  the  parts  is  strictly  rotary  in  every  sense,  ex- 
cept for  the  relation  of  the  pistons  to  the  cylinders,  and  the 
motion  is  as  continuous  as  in  a  turbine.  This  insures  freedom 
from  vibration.  As  the  cylinders  and  crank  case  have  consider- 
able inertia  there  is  no  need  of  the  added  weight  of  a  fly-wheel. 
The  movement  of  the  piston  in  the  cylinder"  bore  is  brought 
about  by  the  difference  in  the  centers  about  which  these  parts 
revolve.  This  gives  cylinder  displacement  without  the  reversal 
of  stresses  or  shock  or.  jar. 

Because  of  the  revolving  cylinders,  the  mixture  is  supplied 
to  the  crank  case  through  a  hollow  shaft,  the  gas  being  drawn 
into  the  cylinder  on  the  suction  stroke  through  an  inlet  valve 
placed  in  the  head  of  the  piston.  As  a  rule,  the  exhaust  is  direct 
to  the  air  through  the  exhaust  valves  and  without  manifolds  or 
mufflers.  The  motion  of  the  cylinders  through  the  air  multiplies 
the  efficiency  of  the  radiating  Fins. 

.  (55)  The  Gyro  Rotary  Motor. 

In  the  Gyro  motor,  made  by  the  Gyro  Motor  Company  of 
Washington,  D.  C.,  are  embodied  all  of  the  principles  of  the 
typical  revolving  motor,  but  with  extensive  improvements  in 
the  design  and  in  the  details.  It  weighs  3^4  poun-ds  per  horse- 
power, complete.  This  light  weight  is  due  to  the  design  of  the_ 
motor  and  to  the  use  of  alloy  steels,  and  is  attained  without 
sacrificing  strength  or  durability. 

Each  cylinder  is  machined  out  of  a  heavy  3^  per  cent  tubular 
nickle  steel  forging  that  weighs  nearly  40  pounds.  After  the  metal 
is  removed  and  the  cylinder  worked  down  to  size,  the  shell  weighs 
but  6y2  pounds.  The  radiating  ribs  on  the  outside  of  the  cyl- 
inder are  machined  out  of  the  solid  bar,  and  are  arranged  in 
helicoid  or  screw-like  formation  around  the  cylinder  barrel. 
This  adds  to  the  strength  of  the  cylinder  and  also  aids  in  the 
circulation  of  the  air.  The  comparative  thickness  of  the  cyl- 
inder wall  may  be  seen  from  Fig.  44.  The  stiffening  effect  of 
the  radiating  ribs  will  also  be  noted.  The  crank  case  to  which 
the  cylinders  are  fastened  is  of  vanadium  steel,  and  is  divided 
into  two  parts.  In  addition  to  supporting  the  cylinders,  the 


134  GAS,  OIL,  AND  STEAM  ENGINES 


Fig.  45.     Section  Through  Rotary  Gyro  Motor. 


GAS,  OIL  AND  STEAM  ENGINES  135 

crank  case  also  serves  as  a  mixing  chamber  for  the  gasoline 
and  air.  By  removing  the  bolts  seen  between  each  cylinder, 
the  entire  working  mechanism  can  be  laid  bare  for  inspection. 
The  exterior  of  the  case  carries  the  exhaust  valve  mechanism 
and  the  ignition  distributer.  The  crank  shaft  is  a  nickel  steel 
forging  with  an  elastic  limit  of  110,000  pounds.  It  is  bored 
hollow  throughout  its  length  and  serves  as  an  intake  mani- 
fold by  conveying  the  mixture  from  the  carbureter,  attached 
to  its  outer  end,  to  the  crank  case. 

The  intake  valves  in  the  heads  of  the  piston  are  mechanically 
operated  by  a  specially  patented  movement  which  consists  of 
two  parts,  a  counter-balancing  member,  and  an  operating  mem- 
ber. The  counter  balance  balances  the  valve  against  the  dis- 
turbing influence  of  the  centrifugal  force,  while  the  operating 
member,  which  is  fastened  to  the  connecting  rod,  controls  the 
opening  or  closing  of  the  valve  by  the  angular  position  of  the 
connecting  rod.  This  valve  action  insures  a  full  opening  of 
the  valve  and  a  full  charge  during  practically  all  of  the  suction 
stroke. 

There  are  two  separate  paths  provided  for  the  exhaust  gases, 
one  being  through  the  auxiliary  exhaust  ports  at  the  end  of  the 
stroke,  and  the  other  path  through  the  exhaust  valve  located  in 
the  cylinder  head.  The  auxiliary  ports  may  be  seen  in  the  cross- 
section  directly  below  the  piston  head  in  cylinders  4  and  5.  The 
auxiliary  ports  are  uncovered  by  the  piston  at  the  inner  end 
of  the  working  stroke,  and  it  is  at  this  point  that  the  greater 
percentage  of  the  exhaust  leaves  the  cylinder.  These  ports  or 
holes  are  formed  on  a  projecting  annular  ring  in  which  enough 
material  is  provided  to  make  up  for  the  strength  lost  by  boring 
the  ports.  As  these  ports  are,  in  the  majority  of  cases,  bored 
at  an  acute  angle  with  the  center  line  of  the  cylinder,  it  is  im- 
possible for  the  cylinder  oil  to  escape. 

All  exhaust  valves  are  operated  by  levers  and  push  rods  con- 
nected to  a  cam  mechanism  on  the  outside  of  the  crank  case. 
A  single  cam  ring  operates  all  of  the  valves  except  where  a 
step-by-step  compression  is  desired.  The  exhaust  mechanism 
is  provided  with  a  simple  device  by  which  the  closing  of  the 
exhaust  valve  may  be  delayed  through  any  portion  of  the  ex- 
haust stroke,  thus  reducing  the  compression  and  adding  to  the 
facility  of  cranking.  The  motor  is  started  with  the  compression 
entirely  released  in  which  condition  it  can  be  spun  about  its 
shaft  with  ease. 

After  giving  the  motor  its  initial   spin,  the  compression  and 


136  GAS,  OIL  AND  STEAM  ENGINES 

spark  are  thrown  in  and  the  engine  begins  its  normal  opera- 
tion. The  compression  release  lever  may  be  used  for  starting 
or  slow  running  and  in  cutting  off  the  power  regardless  of  the 
ignition  advance  or  retard. 

One  connecting  rod,  called  the  "master"  rod,  is  an  integral 
part  of  the  spider  that  contains  the  ball  bearings  of  the  crank 
pin,  thus  controlling  the  angular  relation  between  the  connect- 
ing rods  and  cylinders.  The  remaining  six  rods  are,  of  course, 
articulated  on  the  spider  by  pins  so  that  the  rods  may  move 
in  regard  to  the  spider  when  in  different  parts  of  the  stroke. 
The  shell  of  the  pistons  is  of  a  fine  grade  of  iron,  very  thin  and 
elastic,  so  that  it  may  conform  readily  to  the  outline  of  the  cyl- 
inder bore.  The  head  of  the  piston  consists  principally  of  the 
intake  valve  cage,  the  cage  carrying  the  piston  pin  as  well  as 
the  valve. 

Oil  is  supplied  by  a  positive  pump  that  measures  the  lubri- 
cant in  exact  proportion  to  the  load  on  the  engine.  Both  the 
oil  and  the  gasoline  mixture  enter  the  crank  case  through  the 
hollow  crank  shaft  and  mingle  in  the  form  of  a  vapor.  This 
oil  mist  reaches  every  moving  part  and  results  in  perfect  lubri- 
cation. The  pistons  are  provided  with  oil  shields  which  carry 
the  oil  directly  to  the  cylinder  walls  and  prevent  the  loss  of 
oil  through  the  exhaust  valve. 

Ignition  is  performed  by  a  high  tension  magneto  through  a 
distributer  which  directs  the  current  to  the  proper  cylinder. 
As  in  all  rotary  engines,  the  Gyro  has  an  uneven  number  of 
cylinders  (3,  5,  and  7)  in  order  that  the  cylinders  receive  firing 
impulses  through  equal  angles  of  rotation.  An  even  distribu- 
tion of  firing  is  impossible  with  an  even  number  of  cylinders, 
as  two  adjacent  cylinders,  out  of  six  alternately  fire  together 
and  then  180°  apart.  This  produces  a  very  jerky  turning  move- 
ment, and  is  productive  of  much  vibration.  In  the  seven  cyl- 
inder motor  the  magneto  is  driven  by  gears  having  a  ratio  of 
4  to  7,  and  the  high  tension  current  is  distributed  to  the  cyl- 
inders by  7  brushes,  the  leads  from  the  brushes  being  taken 
direct  to  the  spark  plugs. 

(56)  Gnome  Rotary  Motor. 

The  Gnome  was  the  first  rotary  aviation  motor  built  in 
Europe  and  is  still  one  of  the  most  capable  flight  motors  abroad 
as  its  many  victories  and  records  prove.  It  is  built  in  four 
sizes,  50,  70,  100,  and  140  horse-power,  the  50  and  70  horse- 
power motors  having  7  cylinders,  and  the  100  and  140  horse- 


GAS,  OIL  AND  STEAM  ENGINES 


137 


power,  having  14  cylinders,  which  consist  of  two  rows  of  7 
cylinders  per  row.  The  cylinders  of  all  sizes  rotate  about  a 
stationary  crank  shaft  while  the  pistons  rotate  in  a  circle,  the 
center  of  which  is  the  crank  pin.  Vibration  is  practically  elim- 
inated at  high  speed  as  the  pistons  do  not  reciprocate  in  the 
ordinary  sense  of  the  word,  but  simply  revolve  in  a  circle,  the 
reciprocating  relation  between  the  cylinders  and  pistons  being 
obtained  by  the  difference  in  the  centers  of  the  two  revolving 


Fig.     50.     Cross-Section     Through     the     Seven     Cylinder     Rotary     Gnome 
Motor,    Showing    the    Crank    Shaft    Arrangement    and    Valves. 

systems.  The  cooling  effect  of  the  radiating  ribs  is  greatly 
increased  by  the  air  circulation  set  up'  by  the  rotation  of  the 
cylinders.  This  method  of  cooling  introduces  a  great  loss  of 
power  due  to  the  blower  action  of  the  cooling  ribs,  this  loss 
often  amounting  to  15  per  cent  of  the  output  of  the  engine. 

The  crank  shaft  is  stationary  and  acts  as  a  support  for  the 
engine,  one  end  being  fastened  into  a  supporting  spider  which 
forms  a  part  of  the  aeroplane  frame.  The  crank  shaft  is  hollow 
and  also  serves  to  conduct  the  mixture  from  the  carburetor 


138 


GAS,  OIL  AND  STEAM  ENGINES 


fastened  at  its  outer  end  to  the  crank-case  of  the  motor.  Only 
one  crank  throw  is  provided  on  the  seven  cylinder  engine  as 
the  cylinders  are  all  arranged  in  one  plane  which  passes  through 
the  center  of  the  crank  throw.  In  the  fourteen  cylinder  engine 
where  the  cylinders  are  in  two  rows,  there  are  two  crank  throws, 
one  for  each  row  of  cylinders. 

The  seven  cylinders  are  arranged  radially,  as  will  be  seen 
in  Fig.  50,  each  being  spaced  at  an  equal  distance  from  the 
crank  shaft  and  at  equal  angles  with  one  another,  the  arrange- 
ment in  general  being  similar  to  that  of  the  "Gyro"  motor 
shown  in  the  preceding  section.  All  cylinders  are  turned 


Fig.  51.  Firing  Diagram  of  Seven  Cylinder  Rotary  Motor.  On  Starting 
at  Cylinder  No.  1,  and  Following  the  Zig-Zag  Line  in  the  Direction 
of  the  Arrows,  it  Will  be  Seen  that  Ignition  Occurs  at  Every  other 
Cylinder  at  even  Intervals  Through  Two  Revolutions,  Ending  at 
Cylinder  No.  1. 


out  of  solid  forged  steel  bars,  the  cylinder  walls  being  only 
1.2  millimeters  thick  after  the  machining  operation.  This 
results  in  the  strongest  and  lightest  cylinder  possible  to  build, 
as  all  superfluous  material  is  removed  and  the  chances  of 
defects  in  the  material  are  reduced  to  a  minimum  as  the  char- 
acter of  the  metal  is  revealed  by  the  extended  machining  opera- 
tions. 

As  the  motor  operates  on  the  four  stroke  cycle  system,  an 
odd  number  of  cylinders  is  chosen  in  order  that  the  firing  may 
be  carried  out  through  equal  angles  in  the  revolution  to 
obtain  a  uniform  turning  movement.  Since  a  four  stroke  motor 
must  complete  two  revolutions  before  all  of  the  cylinders  have 


GAS,  OIL  AND  STEAM  ENGINES 


139 


fired,  or  completed  their  "routine  of  events,  it  is  evident  that 
the  number  of  cylinders  must  be  odd  in  order  to  bring  the 
last  cylinder  into  firing  position  in  the  last  revolution.  When 
seven  cylinders  are  used,  the  cylinder  are  fired  alternately  as 
they  pass  a  given  fixed  point,  that  is,  one  cylinder  is  fired,  the 
next  skipped,  the  third  fired,  and  the  fourth  skipped,  and  so 
on  around  the  circle,  so  that  the  firing  order  in  terms  of  the 
cylinder  numbers  is  1,  3,  5,  7,  2,  4,  6.  The  cylinders  fired  in 
the  first  revolution  in  order  are  1,  3,  5,  7,  and  in  the  second 
revolution,  7,  2,  4,  6,  the  cylinder  7  being  common  to  both 
revolutions.  The  cylinders  are  numbered  according  to  their 


Fig.  52.  Firing  Diagram  of  Six  Cylinder  Rotary  Motor.  On  Following 
the  Zig-Zag  Line  it  Will  be  Seen  that  All  of  the  Cylinders  Are  Not 
Fired  at  Equal  Intervals.  In  Some  Cases  Two  Adjacent  Cylinders 
Fire  in  Sequence,  and  in  Others  Two  or  Three  Spaces  are  Jumped. 

position  on  the  engine,  and  NOT  according  to  the  firing  se- 
quence. See  Fig.  51. 

With  a  six  cylinder  engine  it  is  possible  to  fire  the  cylinders 
in  two  ways,  the  first  being  in  direct  rotation;  1,  2,  3,  4,  5,  6 
thus  obtaining  six  impulses  in  the  first  revolution,  and  none 
in  the  second.  The  second  method  is  to  fire  them  alternately, 
1,  3,  5,  2,  4,  6,  in  which  case  the  engine  will  have  turned  through 
equal  angles  between  impulses  1  and  3,  and  3  and  5,  but  through 
a  greater  angle  between  5  and  2,  and  even  again  between  2 
and  4,  and  4  and  6.  See  Fig,  52. 

Mixture  is  drawn  into  the  cylinder  by  the  suction  of  the 
piston  through  an  inlet  valve  in  the  piston  head,  in  practically 


140 


GAS,  OIL  AND  STEAM  ENGINES 


the  same  way  as  in  the  "Gyro"  motor,  but  unlike  the  latter 
motor,  the  valve  is  lifted  by  the  suction  (automatic  valve)  and 
not  by  the  mechanical  actuation  of  the  connecting  rod.  The 
inlet  valve  is  balanced  against  the  effects  of  centrifugal  force 
by  a  small  counter-weight  in  the  piston  head,  and  the  valve  is 
held  normally  on  its  seat  by  a  flat  spring  acting  on  the  valve 
stem.  The  gases  are  brought  into  the  crank  case  from  the 


Fig.    53.     Longitudinal    Section    Through    Gnome    Rotary    Motor. 

carburetor   through    the   hollow    crank-shaft    as    described    else- 
where.   See  Fig.  53. 

All  exhaust  valves  are  located  in  the  cylinder  head  and  are 
actuated  by  long  push  rods  that  are  moved  by  individual  cams 
in  an  extension  of  the  crank  case.  The  exhaust  valves  are 
counter-balanced  against  centrifugal  force  and  are  retained  on 
their  seats  by  a  flat  spring.  The  counter  weights  do  not  entirely 
overcome  the  effects  of  the  centrifugal  force  but  allow  a  slight 
excess  to  exist  which  will  permit  the  engine  to  run  with  a 
broken  spring.  All  of  the  exhaust  gases  escape  directly  to 
the  atmosphere  without  piping  or  mufflers. 


GAS,  OIL  AND  STEAM  ENGINES 


141 


Owing  to  the  fact  that  the  advancing  or  leading  face  of  the 
cylinder  is  cooler  than  the  trailing  face,  the  cylinder  bore  is 
thrown  dut  of  line  by  the  difference  in  expansion  between  the 
two  sides.  Because  of  this  distortion  of  the  bore,  a  special 
form  of  piston  ring  is  used,  which,  by  its  flexibility,  adapts  it- 
self to  variations  in  the  bore.  These  rings  are  of  brass  and  are 
shaped  like  the  pump  leathers  of  a  water  pump  so  that  the  pres- 
sure of  the  explosion  acting  on  the  inside  of  the  ring  tends 


Fig.    54.     Gnome    Motor   on   Testing    Stand.     From    Scientific   American. 

to  force  the  thin  shell  against  the  cylinder.  In  spite  of  this 
precaution,  the  compression  pressure  is  very  low  at  the  best, 
in  the  most  of  cases  not  over  45  pounds  per  square  inch.  The 
exhaust  valve  screws  into  the  end  of  the  cylinder  and  may  be 
removed,  complete  with  its  seat,  for  the  frequent  regrinding 
necessary  to  efficient  operation.  After  the  cylinders  are  ground 
with  the  greatest  care  and  accuracy,  the  finishing  is  carried 
still  further  by  wearing-in  the  cylinder  with  an  actual  piston 
carrying  an  "obturateur"  or  piston  ring. 

The  bushing  into  which  the  spark  plug  screws  is  not  integral 
with  the  cylinder  as  in  a  cast  construction,  but  is  welded  into 


142 


GAS,  OIL  AND  STEAM  ENGINES 


the  side  of  the  cylinder  head  by  means  of  the  autogenous  proc- 
ess. It  is  also  evident  that  this  construction  enables  the  inlet 
valves  to  be  easily  removed,  since  these  screw  into  the  piston 
head.  Both  inlet  and  exhaust  valves  in  the  Gnome  engine  are 
removed  with  the  greatest  ease,  special  socket  wrenches  being 
supplied  for  the  purpose.  The  castor  oil,  which  is  used  as  a 
lubricant,  and  the  gasoline,  are  fed  by  a  positive  acting  piston 
pump  to  the  hollow  crank  shaft.  The  lubricant  and  fuel  then 


Fig.     55.     Gnome     Motor     Running     On     Test     Stand.     From     Scientific 

American. 

pass    through    the    automatic    inlet   valve    in    the    head    of    the 
cylinder. 

The  spark  produced  by  the  high  tension  magneto  is  led 
to  the  proper  cylinder  through  a  brush  that  presses  on  a 
revolving  ring  of  insulating  material  in  which  is  imbedded  7 
metallic  segments,  one  of  the  segments  being  connected  to  a 
corresponding  cylinder.  As  the  distributor  ring  revolves  the 
segments  come  into  contact  with  the  brush  in  the  proper  order, 
The  magneto  is  stationary  and  is  supported  by  a  bracket  in  an 
inverted  position.  A  pinion  on  the  magneto  shaft  meshes  with 


GAS,  OIL  AND  STEAM  ENGINES  143 

a  large  gear  mounted  on  the  revolving  crank  case  so  that  the 
armature  of  the  magneto  always  bears  a  positive  relation  to  the 
piston  position.  As  the  engine  requires  seven  sparks  for  every 
two  revolutions,  or  $l/2  sparks  per  revolution  it  is  evident  that 
the  magneto  must  turn  1.75  times  as  fast  as  the  engine,  if  the 
magneto  is  of  the  ordinary  type  that  generates  two  sparks  per 
revolution.  In  other  words  the  magneto  speed  is  to  the  en- 
gine speed  as  7  is  to  4. 


The    "Indian"    Rotary    Aero    Motor. 

The  arrangement  of  connecting  rods  is  interesting,  the  big 
end  of  one  r.od  being  formed  into  a  cage  for  the  reception  of 
the  crank-pin  ball  race.  The  outer  circumference  of  the  cage 
carries  the  pins  to  which  the  other  six  connecting  rods  are 
fastened.  It  is  necessary  that  one  rod  be  integral  with  the 
cage  to  prevent  its  rotation  in  regard  to  the  cylinders.  An- 
nular ball  bearings  are  used  on  both  the  main  bearings,  for 
the  thrust  bearing  to  take  the  thrust  of  the  propeller,  and  on 
the  large  end  of  the  master  connecting  rod.  The  large  ends 
of  the  auxiliary  connecting  rods  and  the  small  ends  of  all  the 
rods  have  plain  bearings. 


CHAPTER  VI 
TWO  STROKE  CYCLE  ENGINES 

(30)  The  Junker  Two  Stroke  Cycle  Engine. 

The  Junker  two  stroke  cycle  engine  stands  unique  among 
the  large  stationary  units  not  only  in  the  principle  of  its  work- 
ing cycle  but  in  its  construction  as  well,  and  while  it  may  be 
considered  freakish  when  compared  to  standard  practice  it  has 
proved  its  value  in  many  European  installations.  The  combus- 
tion occurs  in  the  center  of  an  open  ended  cylinder  between  two 
pistons  that  are  forced  in  opposite  directions  by  the  expansion 
of  the  gas,  and  as  there  is  a  single  acting  piston  in  each  end 
of  the  cylinder  at  the  end  of  the  stroke,  there  is  no  need  of 
stuffing  boxes,  cylinder  heads  or  valves. 

It  is  apparent  that  by  moving  the  pistons  in  opposite  direc- 
tions, the  effective  piston  velocity  is  twice  that  of  the  actual 
velocity  of  either  of  the  pistons,  and  that  it  is  therefore  possi- 
ble to  gain  a  high  heat  efficiency  at  high  piston  velocities  with 
a  low  rate  of  rotation.  The  double  pistons  increase  the  scaveng- 
ing effects,  reduce  the  losses  to  the  cooling  water  and  increase 
the  efficiency  at  light  loads.  A  marked  reduction  in  weight  over 
the  four  stroke  cycle  engine  is  made  possible  because  of  the 
absence  of  valves  and  valve  gear. 

This  engine  is  of  the  injected  fuel  type  that  is  the  fuel  is 
sprayed  into  the  combustion  chamber  after  the  completion  of 
the  compression  stroke  in  a  manner  similar  to  the  Diesel  en- 
gine. By  prolonging  the  injection  of  fuel  after  the  piston  has 
started  on  the  outward  working  stroke  it  is  possible  to  main- 
tain the  maximum  pressure  due  to  the  combustion  for  a  con- 
siderable period.  This  gives  an  indicator  card  that  is  very 
similar  to  that  of  a  steam  engine  as  the  flat  top  of  the  Junker's 
card  due  to  the  continued  combustion  and  pressure  corresponds 
to  the  admission  line  of  the  steam  engine.  As  ignition  is  caused 
by  the  high  temperature  of  the  compression,  almost  any  low 
grade  oil  may  be  used  even  down  asphaltum  oils  and  coal  tar. 

In  Fig.  8  five  piston  positions  corresponding  to  five  events  are 
shown  by  the  diagrams  a,  b,  c,  d,  e.  From  the  diagrams  one 

144     ' 


GAS,  OIL  AND  STEAM  ENGINES 


145 


may  also  get  an  idea  of  the  arrangement  of  the  principal  parts 
of  the  engine  and  their  relation  to  one  another.  P  and  P2  are 
the  two  pistons,  C  the  open  ended  cylinder,  G  the  connecting 
rod  of  the  inner  piston  P,  H-H  the  two  connecting  rods  of  the 


Fig.    8.     The    Junker    Two    Stroke    Cycle    Engine. 

piston  P2,  I-I  the  side  rods  of  the  piston  P2,  and  V  is  the  three 
throw  crank  shaft  which  is  acted  on  by  the  three  connecting 
rods  H-H-G.  The  piston  P2  is  connected  to  the  side  rods 
through  the  yoke  Y.  It  will  be  noted  that  the  crank  throws 


146  GAS,  OIL  AND  STEAM  ENGINES 

controlling  the  piston  P2  are  180°  from  the  crank  connected  to 
piston  P,  which  causes  the  pistons  to  move  in  opposite  direc- 
tions. 

With  the  pistons  together  at  the  inner  dead  center,  the  space 
between  them  is  filled  with  highly  compressed  air  from  the  pre- 
vious combustion  stroke.  At  this  point  the  fuel  is  injected  into 
the  highly  heated  air,  and  the  expansion  of  the  charge  begins, 
the  combustion  proceeding  under  constant  pressure  during  the 
first  part  of  the  stroke,  or  during  that  part  of  the  stroke  in 
which  the  fuel  is  admitted  to  the  cylinder.  When  the  supply  of 
fuel  is  cut  off  the  working  stroke  continues  by  the  increase  of 
volume,  or  expansion  of  the  gas,  the  gases  being  reduced  to 
nearly  atmospheric  pressure  at  the  end  of  the  stroke  with  the 
pistons  at  the  position  shown  by  diagram  (b).  At  this  point 
the  piston  P.  is  just  opening  the  edge  of  the  exhaust  port  M, 
allowing  the  products  of  combustion  to  escape  to  the  atmos- 
phere through  the  annular  exhaust  passage  that  surrounds  the 
port  M. 

As  the  pistons  continue  to  move  outwards  the  gases  continue 
to  issue  from  the  exhaust  port  at  practically  atmospheric  press- 
ure until  the  position  shown  by  diagram  (c)  is  reached  by  piston 
P2.  At  this  point  P2  is  just  opening  the  inlet  port  N  allowing 
fresh  air  to  enter  the  cylinder  for  the  purpose  of  scavenging  the 
engine.  The  passage  of  the  air  through  the  intake  port  N  and 
out  through  the  exhaust  port  M  continues  until  the  pistons  pass 
the  outer  dead  center,  shown  by  diagram  (d),  and  begin  to 
come  back  on  the  return  stroke.  In  diagram  (e)  the  pistons 
have  traveled  far  enough  to  close  both  ports,  and  as  the  space 
between  them  is  filled  with  pure  air  from  that  furnished  by 
the  port  N,  the  pistons  will  continue  to  move  toward  one  an- 
other on  the  compression  stroke.  When  they  have  reached  the 
end  of  their  travel  as  shown  by  diagram  A,  the  fuel  is  injected 
into  the  cylinder  and  combustion  occurs  due  to  the  temperature 
of  the  high  compression  temperature. 

This  is  the  complete  cycle  of  events  made  in  two  strokes, 
and  it  will  be  noted  that  the  cycle  has  been  accomplished  with- 
out the  use  of  valves.  The  compressed  air  for  scavenging  the 
cylinder  is  provided  by  air  pumps  that  are  driven  from  the  con- 
necting rods  by  a  link  motion.  One  low  pressure  pump  for 
the  scavenging  and  one  high  pressure  pump  for  spraying  the 
fuel  into  the  cylinder  against  compression  are  provided.  Ag 
the  inside  of  the  piston  is  always  exposed  to  the  atmosphere 
through  the  open  end§  of  the  cylinder  and  is  never  exposed 


GAS,  OIL  AND  STEAM  ENGINES 


147 


to  the  heat  of  combustion,  perfect  cooling  is  secured,  and  as  a 
matter  of  course,  perfect  lubrication. 

In  the  two  cylinder  engine  in  which  four  pistons  are  used, 
the  cylinders  are  arranged  in  tandem  with  the  two  adjacent 
pistons,  and  the  two  outer  pistons  connected  respectively.  In 
fact  the  second  cylinder  pistons  are  duplicates  of  those  just 
shown  and  are  connected  to  the  linkage  in  such  a  manner  a-s 
to  have  the  corresponding  pistons  in  one  cylinder  act  with 
the  corresponding  pistons  in  the  second. 

(34)  Koerting  Two  Stroke  Cycle  Engine. 

One  of  the  most  prominent  of  the  two  stroke  cycle  scaveng- 
ing engines  built  for  heavy  stationary  service  is  the  Koerting 
engine.  Because  of  its  peculiar  scavenging  arrangement,  and 


F-ll.     Koerting    Two    Stroke    Cycle    Engine    with    Scavenging    and 
Charging    Cylinders. 

as  it  is  of  the  double  acting  type,  it  will  serve  to  illustrate  the 
cycle  of  that  class  of  engine  equipped  with  independent  air 
pumps.  Several  of  these  engines  are  in  use  in  Europe  that 
have  an  output  of  over  4,000  horse-power,  the  general  arrange- 
ment of  which  is  the  same  as  shown  in  the  accompanying  dia- 
gram Fig.  F-ll. 

Since  the  engine  is  double  acting,  two  similar  combustion 
chambers  are  provided  at  each  end  of  the  piston  as  shown  by 
C  and  Ci,  and  as  each  of  the  chambers  gives  one  impulse  per 
revolution  because  of  the  two  stroke  cycle,  the  single  cylinder 
shown  in  the  figure  delivers  two  impulses  per  revolution  to  the 
crank-shaft.  In  order  to  have  one  exhaust  port  serve  for  both 
combustion  chambers,  the  annular  port  E  is  placed  in  the  cen- 
ter of  the  cylinder  so  that  it  is  alternately  opened  to  C  and  then 
Ci  as  the  piston  travels  to  and  fro,  the  port  being  covered  by 


148  GAS,  OIL  AND  STEAM  ENGINES 

the  piston  at  intermediate  points  in  its  travel.  As  the  piston 
must  cover  the  port  for  a  considerable  portion  of  the  stroke, 
it  is  made  very  long,  nearly  as  long  as  the  stroke.  The  piston 
rod  R  that  connects  the  piston  with  the  crank  passes  through 
the  cylinder  head  of  chamber  Cu  surrounded  by  a  gas  tight 
packing  that  prevents  the  leakage  of  the  charge  from  Ci. 

Unlike  the  ordinary  type  of  two  stroke  cycle  engine,  the  two 
combustion  chambers  are  provided  with  mechanically  operated 
inlet  valves,  V-Vj-Va-Vs  that  are  opened  at  definite  points  in 
the  stroke  by  the  lay  shaft  X  which  is  driven  from  the  crank 
shaft.  As  the  exhaust  port  E  serves  all  of  the  functions  of  an 
exhaust  valve,  there  are  no  valves  provided  at  this  point.  Ex- 
haust pipes  connected  to  E  carry  the  burnt  gases  to  the  atmos- 
phere. 

Two  auxiliary  air  pumps  of  the  double  acting  type  are  pro- 
vided, shown  at  A  and  A,,  one  pumping  gas  and  the  other  air. 
They  are  driven  from  the  crank-shaft  through  the  connecting 
rod  Y,  and  are  proportioned  so  that  together  they  force  a  mix- 
ture of  the  correct  proportion  for  complete  combustion  into  the 
working  cylinder  at  a  pressure  of  about  ten  pounds  per  square 
inch.  Air  and  gas  are  compressed  on  one  side  of  each  pump 
piston  in  the  spaces  B  and  B2,  and  the  air  and  gas  are  drawn 
in  on  the  other  side  as  at  H  and  H2.  The  connections  from  the 
compressor  cylinders  to  the  working  cylinder  are  arranged  so 
that  the  two  crank  ends  of  the  compressor  C3^1inders  discharge 
into  the  crank  end  of  the  working  cylinder,  and  the  front  ends 
of  the  compressors  discharge  into  the  front  end  of  the  working 
cylinder,  the  exact  moment  of  discharge  being  controlled  by 
the  inlet  valves  V-Vi-V,-V3.  The  pumps  are  arranged  so  that 
only  pure  air  is  admitted  at  first  in  order  to  force  the  products 
of  combustion  through  the  exhaust  port  so  that  they  will  not 
contaminate  the  following  mixture  of  air  and  gas.  The  inlet 
valve  opens  immediately  after  the  piston  of  the  working  cylinder 
uncovers  the  port  E  and  reduces  the  pressure  of  the  burnt  gases 
to  that  of  the  atmosphere. 

By  the  action  of  the  admission  control,  the  scavenging  air 
first  admitted,  is  prevented  from  mixing  with  the  residual  gas 
from  the  previous  explosion,  and  in  the  same  way  the  device 
prevents  the  loss  of  fuel  through  the  exhaust  ports,  thus  over- 
coming the  principal  objections  of  the  simple  two  stroke  types 
described  earlier  in  this  chapter.  The  compressor  cylinders  pro- 
vide only  enough  air  and  mixture  for  one  stroke  and  no  reser- 
voir is  provided  for  a  surplus  of  air  or  mixture. 


GAS,  OIL  AND  STEAM  ENGINES  149 

As  the  piston  moves  forward,  on  the  compression  stroke  and 
covers  the  exhaust  port,  the  inlet  valves  also  close,  and  the 
compressor  pistons  arrive  at  the  end  of  their  stroke  so  that 
no  more  air  or  mixture  is  delivered  to  the  inlet  valves.  At  the 
end  of  the  compression  stroke  ignition  occurs  and  the  ex- 
pansion or  working  stroke  begins.  The  piston  again  moves  to 
the  right  on  the  working  stroke  until  the  front  edge  uncovers 
the  port  E  where  the  exhaust  gases  escape  to  the  atmosphere. 

The  valve  gear  on  the  gas  compressing  cylinder  is  arranged 
so  that  no  gas  is  delivered  to  the  inlet  valves  of  the  working 
cylinder  until  the  air  cylinder  has  provided  sufficient  air  to  in- 
sure perfect  scavenging  of  the  products  of  combustion,  this  pre- 
venting the  fuel  from  becoming  contaminated  with  the  burnt  gas. 
Speed  regulation  for  varying  loads  is  effected  by  shifting  the 
valve  gear  of  the  gas  pump  so  that  the  gas  is  delivered  at  an 
earlier  or  later  period  in  the  stroke  of  the  working  piston,  thus 
causing  a  variation  in  the  quantity  of  gas  delivered  to  the  work- 
ing cylinder.  This  is  controlled  by  the  governor  directly 
on  the  valve  gear  of  the  pump  or  upon  a  by-pass  in  the  pump 
cylinder  or  both.  The  by-pass,  when  open  returns  all  of  the 
gas  in  the  passage  leading  to  the  inlet  valve,  that  is  beyond 
a  certain  pressure  to  the  cylinder,  so  that  the  gas  is  delivered 
to  the  cylinder  at  a  constant  pressure,  and  therefore  in  propor- 
tion to  the  load  and  point  of  cut  off. 

This  method  of  governing  produces  a  mixture  that  varies  in 
richness  with  the  different  loads  that  are  carried  by  the  engine, 
but  as  the  air  enters  the  cylinder  first  and  is  prevented  from 
mixing  to  any  extent  with  the  gas  by  the  shape  of  the  cylinder 
heads,  the  igniting  value  of  the  mixture  is  not  disturbed  par- 
ticularly as  the  rich  gas  remains  in  the  cylinder  heads  and  in 
contact  with  the  igniters. 

Like  all  large  engines,  the  Koerting  is  started  by  compressed 
air  taken  from  a  reservoir.  A  special  starting  valve  is  provided 
for  each  end  of  the  cylinder  which  is  operated  from  the  cam 
shaft  by  means  of  an  eccentric.  The  air  valves  may  be  thrown 
in  or  out  of  gear  by  a  clutch. 

(57)  Two  Stroke  Cycle  Rail  Motor  Cars. 

A  unique  application  of  the  two  stroke  cycle  motor  will  be 
seen  in  Fig.  56  which  shows  a  Fairbanks-Morse  two  stroke 
cycle  motor  direct  connected  to  the  driving  wheel  of  a  railway 
motor  car.  The  three  cylinders  are  mounted  between  the 
driving  wheel  with  the  ends  of  the  axle  terminating  in  the 


150  GAS,  OIL  AND  STEAM  ENGINES 

crank  cases  of  the  motors.  Access  to  the  bearings  is  had 
through  a  cover  on  the  crank-case.  The  simplicity  of  this 
motor  and  its  freedom  from  valves,  cams,  springs,  gears,  and 
other  trouble  causing  parts  makes  it  particularly  adapted  for 
the  service  that  it  performs  in  the  hands  of  unskilled  track 
laborers.  As  there  is  no  water  to  freeze  or  leak,  and  as  the 
lubricant  is  mixed  with  gasoline,  the  car  needs  very  little  more 
attention  than  the  old  type  hand  car. 

The  car  is  started  by  opening  the  gasoline  supply  cock,  clos- 
ing the  ignition  switch,  and  pushing  the  car  along  the  track 
until  the  first  explosion  occurs.  The  speed  is  controlled  in  the 
usual  manner  by  means  of  the  spark  advance  and  throttle.  As 
the  motor  is  of  the  two  stroke  cycle  type,  it  may  be  reversed 


Fig.     56.     Two     Stroke     Cycle     Fairbanks     Motor     for     Driving     Railway 
Section    Cars. 

by  simply  changing  the  position  of  the  timer  without  the  use 
of  the  gears.  The  speed  is  the  same  in  either  direction.  By 
the  use  of  three  cylinders;  three  impulses  are  obtained  per  revo- 
lution which  gives  a  distribution  of  power  equal  to  that  of  the 
ordinary  six  cylinder,  four  stroke  cycle  automobile  motor. 

For  larger  cars  built  for  carrying  large  gangs  of  men,  a  three 
cylinder  motor  is  used  which  drives  through  a  clutch  and  gears, 
similar  to  that  used  on  automobiles.  It  is  located  near  the 
center  of  the  axle  and  is  supported  on  a  frame  that  is  independ- 
ent of  the  car  proper.  This  motor  unit  is  easily  removed  from 
the  car  for  inspection  with  all  of  the  parts  intact.  A  universal 
coupling  is  provided  on  the  motor  shaft  to  prevent  strains  due 
to  changes  in  the  alignment  from  being  thrown  into  the  motor. 
The  motor  of  this  car  is  started  with  a  crank,'  and  may  be  left 
standing  with  the  motor  running.  As  .with  the  two  cylinder 
car,  the  engine  is  reversible,  and  is  lubricated  by  mixing  the 
lubricating  oil  with  the  gasoline. 


GAS,  OIL  AND  STEAM  ENGINES 


151 


(58)  Rotating  Cylinder  Two  Stroke  Cycle  Motor. 

An  unusual  type  of  two  stroke  cycle  engine  is  that  designed 
by  M.  Farcot  for  aeronautic  work.  It  is  of  the  rotating  cyl- 
inder type  in  which  the  cylinders  rotate  about  a  stationary 


Fig.   63.     Farcot  Rotary  Two    Stroke   Motor. 

crankshaft,  and  unlike  all  previous  two  stroke  motors,  whether 
of  the  revolving  or  stationary  cylinder  type,  no  initial  compres- 
sion is  performed  either  in  the  crank-case  or  otherwise. 


152  GAS,  OIL  AND  STEAM  ENGINES 

Undoubtedly  the  two-cycle  rotating  multi-cylinder  engine  has 
a  future  when  some  of  the  particularly  difficult  designing  prob- 
lems involved  in  its  production  have  been  successfully  tackled. 
Crank  case  compression  has  had  its  devotees,  but  so  far  it  has 
entailed  the  use  of  a  low  compression,  owing  largely  to  the 
difficulties  involved  in  lubricating  the  bearings  and  maintain- 
ing gas-tight  joints,  besides  other  defects.  Some  of  these  bar- 
riers appear  to  have  been  surmounted  in  this  design. 

Fig.  63  of  the  accompanying  drawings  is  a  sectional  side  ele- 
vation of  the  engine,  which,  it  will  be  seen,  is  similar  in  gen- 
eral disposition  to  the  usual  arrangement  of  the  rotating  cyl- 
inder type.  In  this  particular  case,  however,  the  short  end  A 
of  the  stationary  crankshaft  is  reduced  in  diameter  at  B,  and 
on  this  part  are  mounted  ball  bearings  C  carrying  the  circular 
casing  of  a  rotating  centrifugal  blower  D.  To  the  inner  end 
of  the  hub  of  this  blower  is  attached  a  gear  wheel  E,  the  teeth 


Fig.   64.     Farcot   Fan    Plates. 

of  which  mesh  with  small  intermediate  pinions  carried  on  a 
spider  F  attached  to  the  crankshaft.  These  pinions  are  in 
turn  driven  by  an  internally  toothed  ring  G  attached  to  the 
hub  of  the  crank  case  H.  Thus  the  blower  D  is  driven  in  the 
opposite  direction  to  the  crank-case  and  at  a  higher  speed.  In 
the  interior  of  the  blower  casing  radial  blades  K  are  provided. 

A  hollow  annular  casing  L  is  bolted  to  the  cylinders,  and 
communicates  with  their  interiors  by  means  of  inlet  ports  M 
covered  and  uncovered  by  the  pistons. 

The  blower  casing  D  has  on  either  side  circumferentially 
flanged  rings  N,  which  are  a  running  fit  in  circular  register 
slots  provided  in  the  annular  casing  L  and  its  cover  plate  P, 
in  order  to  provide  a  gas-tight  joint  between  the  opposite  re- 
volving casings  D  and  L.  Fan  blades  Q  are  also  provided  in 
the  casing  L  to  accelerate  still  further  the  incoming  gas.  The 
arrangement  of  the  two  sets  of  blades  is  made  clear  in  the 
sectional  sketch  (Fig.  64).  It  will  be  realized  that  by  means  of 
this  compound  blower  device  a  considerable  pressure  can  be 
attained. 

The  crankshaft  is  drilled  to  provide  a  feed  for  the  gasoline, 


GAS,  OIL  AND  STEAM  ENGINES  153 

which  is  atomized  by  a  device  R  in  the  large  central  opening 
of  the  blower  casing  D  by  means  of  pressure  fed  from  the 
annular  casing  L  through  suitable  leads  S. 

As  each  piston  nears  the  bottom  of  its  stroke,  exhaust  ports 
T,  provided  with  expansion  cones  for  the  purpose  of  increasing 
the  velocity  of  the  exhaust  gases,  are  opened.  The  inlet  port 
M  is  then  uncovered,  and  the  compressed  charge  rushes  into 
the  combustion  chamber. 

The  general  design  of  the  engine  is  made  plain  by  Fig.  63, 
but  there  is  one  other  point  to  which  reference  should  be  made, 
and  that  is  the  provision  of  rings  V,  one  on  either  side  of  the 
cylinders,  to  enhance  the  strength  of  the  construction. 

Although  the  difficulty  of  compression  appears  to  have  been 
cleverly  tackled  in  this  invention,  the  possibility  of  the  com- 
pressed mixture  in  the  inlet  casing  and  blower  becoming  ignited 
at  the  moment  of  admission  by  a  residue  of  exhaust  gas  in  the 
combustion  chamber  still  exists.  However,  the  effect  of  such 
a  backfire  should  not  prove  quite  so  serious  as  in  some  de- 
signs. Apart  from  other  considerations,  owing  to  the  large 
area  of  the  blower  intake,  such  an  occurrence  should  merely 
have  a  more  or  less  elastic  braking  effect. 

(60)  Gnome  Radial  Two  Stroke  Motor. 

The  builders  of  the  famous  Gnome  four  stroke  cycle  rotary 
motor,  Sequin  Freres,  have  recently  developed  a  radial  two 
stroke  cycle  motor  that  bids  fair  to  supplant  their  original  type. 
Referring  to  the  diagramatic  cross-sections  which  show  only 
a  single  cylinder  unit,  a  very  long  tubular  piston  will  be  seen 
that  is  divided  into  two  independent  chambers,  A  and  B.  Both 
chambers  are  placed  in  communication  with  the  outside  space, 
C  and  D. 

The  upper  end  of  the  piston  is  continued  above  the  top  divi- 
sion head  of  the  chamber  A,  and  the  extension  is  provided  with 
the  slot  F.  Near  the  center  of  the  piston,  the  walls  of  the 
piston  are  run  out  into  a  flat  circular  plate  or  trunk  piston  E, 
which  is  the  actual  piston  head  that  receives  the  force  of  the 
explosion.  The  piston  E  reciprocates  in  the  large  cylinder  H, 
which  is  reduced  at  its  upper  end  to  the  diameter  of  the  main 
piston  barrel,  for  which  it  affords  a  sliding  support,  or  guide, 
and  also  serves  to  aid  the  exhaust  port  closure.  The  lower 
end  of  the  cylinder  H  is  enlarged  in  diameter  as  shown  by  K 
so  that  a  clear  annular  space  is  left  between  the  cylinder  walls 
and  the  piston  head  E,  when  the  latter  is  at  the  bottom  of  the 


154 


GAS,  OIL  AND  STEAM  ENGINES 


stroke.  The  cylinder  diameter  is  then  reduced  to  the  diameter 
of  the  main  piston  barrel. 

The  motor  operates  as  follows: 

Suppose  the  piston  to  be  ascending  (Fig.  1),  compressing  the 
mixture  above  the  piston  head  in  the  cylinder  E,  and  at  the 
same  time  the  volume  of  the  space  M,  below  E,  is  being  in- 
creased until  the  piston  reaches  the  position  shown  in  Fig.  2. 

Referring  to  Fig.  1;  the  interior  chamber  A  of  the  piston  is 
in  direct  communication  through  the  holes  C  with  the  space 


Fig.   65.     Gnome   Rotary  Two   Stroke  Motor   Diagram.      Diagrams  1   and  2. 

M,  consequently  as  the  piston  goes  up,  a  partial  vacuum  will 
be  formed  in  these  two  chambers.  When  the  piston  reaches  the 
top  of  its  stroke  as  shown  in  Fig.  2,  the  holes  D  in  the  lower 
end  B  of  the  piston  are  uncovered  as  they  rise  into  the  in- 
creased diameter  of  the  cylinder,  and  therefore  the  mixture  is 
sucked  in  from  the  crank  case  until  the  chambers  A  and  M  are 
filled  to  atmospheric  pressure. 

The  spark  now  occurs  at  the  plug  S,  and  the  explosion  takes 
place,  driving  the  piston  downwards  as  shown  by  Fig.  3,  just 


GAS,  OIL  AND  STEAM  ENGINES 


155 


before  the  exhaust  takes  place.  The  volume  of  the  chamber 
M  has  now  been  decreased  with  the  result  that  the  mixture  will 
have  been  compressed  into  the  chamber  A. 

In  Fig.  4,  the  piston  has  now  reached  the  bottom  of  the 
stroke,  and  the  ports  F  have  opened  as  the  slots  carry  below 
the  upp'er  end  of  the  cylinder  where  the  bore  is  increased.  At 
the  same  time,  as  the  piston  plate  E  passes  the  bottom  of  the 
cylinder  H  into  the  enlarged  diameter  K,  the  compressed  mix- 
ture in  A  and  M  rushes  through  the  annular  space  opened 


Gnome    Rotary,    Diagrams    3    and    4. 

around  E  into  the  combustion  chamber  and  drives  out  the 
residual  burned  gases  which  still  remain  after  the  explosion. 
On  starting  the  second  revolution  the  piston  rises  and  the 
cycle  repeats  as  shown  by  Fig.  1. 

This  engine  may  be  built  with  any  number  of  the  cylinder 
units  described,  preferably  with  an  uneven  number,  as  in  the 
case  of  the  Gnome  radial  four  stroke  cycle,  and  with  twice  the 
number  of  impulses  of  the  four  stroke  type  a  very  uniform 
turning  movement  should  be  had. 


156  GAS,  OIL  AND  STEAM  ENGINES 


m  m 


m   mm  mm  m 


Fig.  64-b.  Roberts  Two  Stroke  Aero  Motor  Using  a  Rotating  Tubular 
Valve  that  Controls  the  Mixture  from  the  Carburetor  so  that  it 
Enters  Only  One  Crank  Case  at  a  Time.  This  Gives  Each  Cylinder 
an  Equal  Charge  of  Gas. 


Fig.  64-c.  Roberts  Distributor  Valve.  The  Ports  Are  Cut  in  the  Valve 
so  that  Only  One  Crank  Case  is  in  Communication  with  the  Car- 
buretor at  Any  One  Time.  The  Central  Hole  Connects  with  the 
Carburetor. 


GAS,  OIL  AND  STEAM  ENGINES 


157 


Since  the  valves  are  the  parts  that  give  the  most  trouble 
in  the  four-stroke  cycle  Gnome,  this  motor  should  be  better 
adapted  for  aviation  than  the  original  type  of  Gnome. 

(62)  Variable  Speed  Two  Stroke  Motor. 

A  variable  speed  two  stroke  cycle  motor  is  described  by 
C.  Francis  Jenkins  in  the  Scientific  American  that  seems  to 


Fig.    66.     Jenkins    Two    Stroke    Cycle    Motor. 

solve  many  of  the  problems  encountered  in  designing  a  two 
stroke  cycle  motor  for  automobile  purposes.  As  is  well  known, 
the  present  design  of  the  crank-case  compression  type  is  waste- 
ful of  fuel,  and  ignites  irregularly  at  low  speeds  and  light  run- 
ning, and  as  nearly  all  automobiles  are  well  throttled  for  a 
greater  portion  of  the  time  it  means  that  this  type  of  motor 
is  working  under  the  greatest  disadvantage. 

Since  the  greater  part  of  the  trouble  is  due  to  the  dilution  of 
charge   by   the   residual   gases,    and   as   the    spark   plug   of   the 


158  GAS,  OIL  AND  STEAM  ENGINES 

motor  is  situated  in  the  most  diluted  portion  of  the  gas,  it 
would  seem  that  a  change  of  spark  plug  location,  or  a  change 
in  the  circulation  of  the  fresh  mixture  in  the  cylinder  would  be 
a  great  aid  in  remedying  the  difficulty.  With  the  spark  con- 
tinually in  contact  with  fresh  undiluted  mixture  it  would  be 
possible  to  run  it  as  low  speeds  as  with  the  four  stroke  motor, 
with  a  corresponding  increase  in  the  efficiency,  and  opportunity 
to  run  with  a  constant  advance  of  the  point  of  ignition.  This 
is  accomplished  by  any  or  all  of  the  following  conditions: 

(1.)     By  keeping   good   gas   separate   from   bad. 

(2.)     By  placing  the  spark  near  the  intake  port. 

(3.)  By  leaving  the  plug  in  its  present  position  and  deflect- 
ing the  fresh  gas  to  meet  it. 

(4.)     By  changing  the  location  of  the  inlet  port. 


Fig.     58-a.     Two     Cylinder    Marine     Engine,    of    the    Two     Stroke    Type. 
Built    By    Fairbanks-Morse    and    Company. 

In  the  motor  invented  and  described  by  Mr.  Jenkins,  the 
method  given  by  (4)  is  adopted  as  shown  by  Fig.  66,  in  which 
the  spark  plug  is  placed  at  the  point  of  admission  of  the  gas 
and  in  a  confined  passage.  The  operation  of  the  motor  is 
as  follows: 

Carbureted  gas  is  drawn  into  crank-case  from  the  carburetor 
(not  shown)  in  the  usual  manner,  i.  e.,  by  the  upward  move- 
ment of  the  piston;  and  by  its  downward  movement  is  forced 
through  the  rectangular  port  in  the  wall  of  the  piston  into  the 
combustion  passage  within  the  water-jacket  when  the  port  in 


GAS,  OIL  AND  STEAM  ENGINES  159 

the  piston  wall  registers  with  the  lower  end  of  this  combustion 
passage,  and  drives  ahead  of  it  the  bad  gas  remaining  after  the 
previous  explosion.  If  the  throttle  is  wide  open  the  combus- 
tion space  above  the  piston  will  be  completely  filled,  and  on  the 
ignition  of  the  charge  the  maximum  pressure  will  be  exerted  on 
the  piston.  If,  however,  the  throttle  is  but  slightly  open,  the 
combustion  passage  only  may  be  filled  and  none  overflow  into 
the  combustion  space  above  the  piston.  This  small  charge  will 
be  just  as  efficient  in  proportion  to  its  volume  as  was  the  large 
charge,  for  it  was  compressed  to  practically  the  same  extent  and 


Fig.  64-d.  Rpberts  Cylinder  Showing  Cellular  Screen  in  the  Intake 
Port.  This  Screen  Prevents  Crank  Case  Fires  by  Chilling  the  Cyl- 
inder Flame  Before  it  Enters  the  Crank  Case. 

none  was  mixed  with  the  bad  gas  of  the  previous  explosion. 
It  will,  therefore,  be  obvious  that  the  spark-plug  is  always  swept 
by  the  fresh  charge,  be  it  large  or  small,  and  the  ignition  will 
be  just  as  certain  in  one  case  as  in  the  other,  although  the 
charge  and  consequent  impulse  may  be  only  just  sufficient  to 
keep  the  engine  turning  over,  and  without  missing  a  single 
explosion. 

In  the  motor  built  to  test  and  demonstrate  this  design, 
provision  was  made  for  a  second  spark-plug  to  be  located  in 
the  top  of  the  cylinder  for  speed  work,  if  this  was  found  nec- 
essary. No  opportunity  has  yet  been  had  for  making  track 
tests,  though  without  regret,  as  this  two-cycle  motor  will  run 
idle  without  missing  or  "stuttering,"  which  was  the  thing  here- 
tofore impossible. 


CHAPTER  VII 
OIL  ENGINES 
(31)  Diesel  Oil  Engine. 

The  Diesel  engine  marks  the  greatest  progress  in  the  internal 
combustion  field  made  in  the  last  few  years.  It  marks  a  dis- 
tinct advance  in  both  thermal  efficiency,  and  in  the  character 
of  the  fuel  that  it  has  made  a  commercial  possibility.  By  the 
use  of  cheap  fuel  heretofore  unavailable  for  any  type  of  prime 
mover,  such  as  the  asphaltum  residual  oils,  coal  tar,  etc.,  it 
has  lowered  the  cost  of  power  production  to  a  point  where  it 
is  unapproached  by  any  type  of  heat  engine.  Besides  its  thermal 
efficiency,  the  engine  is  free  from  the  annoyances  due  to  delicacy 
of  the  auxiliary  appliances  such  as  the  carburetor,  and  ignition 
system  which  are  indispensable  with  the  ordinary  type  of  gaso- 
line engine. 

This  engine  belongs  to  that  type  of  engine  in  which  combus- 
tion takes  place  at  constant  pressure  (Brayton  Cycle),  that  is 
the  combustion  pressure  is  maintained  at  a  constant  value  for 
a  considerable  distance  on  the  working  stroke  of  the  piston. 
This  method  differs  from  the  Otto  cycle  in  which  the  combus- 
tion proceeds  at  a  constant  volume,  or  the  type  in  which  com- 
bustion is  completed  before  the  piston  moves  forward  on  the 
working  stroke. 

In  the  Diesel  cycle  the  first  stroke  of  the  piston  draws  pure 
air  into  the  cylinder;  the  piston  then  moves  forward  on  the 
compression  stroke,  compressing  the  air  to  500  or  600  pounds  per 
square  inch  and  raising  the  temperature  of  the  air  to  about  1,000 
degrees  C,  the  exact  temperature  and  pressure  depending  on 
the  character  of  the  fuel  used  in  the  engine.  The  high  pressure 
is  obtained  by  using  a  small  clearance  space  in  the  end  of  the 
cylinder.  At  the  end  of  the  compression  stroke  a  spray  of  oil 
is  injected  into  the  cylinder  which  is  instantly  ignited  by  the 
high  temperature  of  the  compressed  air. 

The  oil  continues  to  burn  as  long  as  it  is  sprayed  into  the 
cylinder,  this  period  being  from  one-quarter  to  one-third  of 
the  working  stroke.  After  the  oil  is  cut  off,  the  hot  gas  is  ex- 

160 


GAS,  OIL  AND  STEAM  ENGINES 


161 


panded  to  the  end  of  the  stroke  at  which  point  the  pressure  is 
very  considerably  reduced  due  to  the  mechanical  work  per- 
formed. It  should  be  noted  that  the  type  of  engine  just  de- 
scribed performs  the  complete  cycle  in  four  strokes,  the  fourth 
stroke  being  the  scavenging  stroke  as  in  the  ordinary  four 
stroke  cycle  engine.  While  the  four  stroke  cycle  type  of  Diesel 
engine  is  by  far  the  most  common  type,  it  is  also  built  as  a  two 
stroke  cycle  that  is  similar  to  the  two  stroke  cycle  gas  engine 
previously  described  except  that  pure  air  is  received  and  com- 
pressed in  the  air  compressor  in  place  of  the  combustible  mix- 
ture. 

It  will  be  noted,  that  as  there  is  no  fuel  in  the  cylinder  dur- 
ing the  compression  stroke  that  there  is  no  danger  from  pre- 
ignition  from  an  over  heated  charge,  nor  is  there  trouble  from 


Fig.  9.     Cross   Section   of  Four   Stroke  Cycle   Diesel   Engine.     The   Center 
Valve  is  the  Fuel  Admission  Valve. 

decomposed  fuels  due  to  a  gradually  increasing  temperature  so 
often  met  with  in  oil  engines  that  compress  the  entire  mixture. 
As  the  clearance  space  is  exceptionally  small  there  is  a  minimum 
of  residual  gas  held  in  the  cylinder  after  the  explosion  with  the 
result  that  the  fuel  is  completely  consumed,  and  that  a  full 
charge  is  taken  'into  the  cylinder. 

The  speed  and  output  are  regulated  by  controlling  the  point 
in  the  working  stroke  at  which  the  oil  spray  is  cut  off,  and  as 
this  has  no  effect  on  the  maximum  pressure  developed  in  the 
cylinder,  as  in  the  case  of  the  ordinary  gas  engine  control,  the 
pressure  charge  under  varying  loads  is  not  so  severe.  Be- 
cause of  the  high  compression,  and  the  continued  combustion, 
there  is  a  very  gradual  increase  of  pressure.  Since  the  amount 
of  pure  air  admitted  to  the  cylinder  is  the  same  at  no  load  as 
at  full  load  there  is  always  sufficient  air  for  the  complete  com- 
bustion of  the  fuel,  and  as  there  is  a  constant  compression 


162 


GAS,  OIL  AND  STEAM  ENGINES 


pressure  there  is  a  constant  ignition  temperature  and  constant 
quantity -of  the  working  medium.  Because  of  the  high  com- 
pression obtained  by  the  Diesel  type,  it  has  an  efficiency  that 
is  far  beyond  that  of  any  other  form  of  internal  combustion 
motor. 


Fuel    Nozzle   of   the   Koerting   Diesel    Engine    Showing    Operating    Cam   and 
Lever,     and    Compressed    Air     Connection. 

Since  the  fuel  is  introduced  gradually  into  the  combustion 
chamber  the  combustion  pressure  rises  very  slowly  so  that  it 
is  not  an  explosive  engine  in  any  sense  of  the  word,  the  com- 
bustion pressure  rising  steadily  from  the  compression  pressure 
to  the  maximum  in  porportion  to  the  supply  of  fuel.  In  the 
ordinary  type  of  gas  engine  with-  a  compression  pressure  of 
from  60  to  70  pounds  per  square  inch  the  pressure  rises  abruptly 
to  about  three  and  one-half  times  the  compression  pressure, 


GAS,  OIL  AND  STEAM  ENGINES 


163 


with  a  correspondingly  rapid  drop  in  the  pressure  on  the  ex- 
pansion stroke.  In  the  Diesel  engine  the  drop  of  pressure  in 
expansion  is  much  more  gradual,  the  indicator  diagram  expan- 
sion curve  being  nearly  horizontal.  The  uniform  pressures  thus 
obtained  result  in  smooth  action  and  even  driving  power,  ob- 
tained with  no  other  type  of  engine. 


Fuel    Pump    of    Koerting    Diesel    Engine    with    Operating    Cam. 

As  the  fuels  used  vary  from  the  lightest  hydrocarbons  to  the 
heaviest  crude  oils,  there  are  many  types  of  oil  injection  valves 
in  use,  the  valves  being  in  general  divided  into  two  classes, 
those  in  which  the  oil  is  vaporized  mechanically  by  the  pres- 
sure of  a  force  pump,  and  those  in  which  the  fuel  is  vaporized 
by  the  atomizing  effect  of  compressed  air.  Atomization  by  com- 
pressed air  is  however,  the  most  common  method  since  less 
trouble  is  experienced  with  the  air  pumps  than  with  the  liquid 
force  pumps.  The  compressed  air  is  supplied  by  pumps  that 


164  GAS,  OIL  AND  STEAM  ENGINES 

are  either  operated  by  the  main  engine  or  by  an  independent 
compressor  engine. 

The  fuel  valve  is  a  plug  screwed  into  the  cylinder  containing 
an  inwardly  opening  check  valve  in  the  inward  end.  The  hole 
in  the  center  of  the  plug  receives  the  oil  charge  under  a  few 
pounds  pressure  from  the  tanks,  during  the  compression  stroke 
of  the  engine,  and  at  the  end  of  the  compression  stroke,  a  blast 
of  air  at  a  pressure  of  about  250  pounds  above  the  com- 
pression pressure  blows  it  into  the  cylinder  in  the  form  of  a 
fine  spray.  Injection  valves  of  the  forced  feed  type  consist  of 
a  plug  with  a  small  passage  and  a  needle  valve  for  regulating 
the  spray.  Fuel  is  pumped  into  the  valve  at  about  250 -pounds 
above  the  compression  pressure  of  the  engine  by  a  small  single 
acting  pump  which  is  built  so  that  the  length  of  the  stroke 
may  be  adjusted  to  meet  the  load.  In  practice  the  length  of 
stroke  is  regulated  by  the  governor,  so  that  the  full  contents 
of  the  pump  are  delivered  at  full  load,  and  a  reduced  amount 
with  a  short  stroke  at  small  loads.  On  issuing. from  the  fuel 
nozzle,  the  liquid  strikes  a  gauze  screen  by  which  it  is  broken 
up  into  very  fine  spray. 

Fluidity  is  practically  the  only  factor  that  governs  the  quality 
of  fuel  that  may  be  used  with  the  engine,  since  exceptionally 
heavy  oils  and  tars  cannot  be  successfully  sprayed.  In  Fig.  9 
is  shown  a  cross-section  of  a  Diesel  engine  cylinder  in  which 
the  center  valve  in  the  cylinder  head  is  the  fuel  valve,  and  the 
valves  to  the  right  and  left  are  the  air  inlet  and  exhaust  valves 
respectively.  The  two  latter  valves  correspond  to  the  inlet  and 
exhaust  valves  of  the  Otto  cycle  engine. 

Compressed  air  is  used  in  starting  the  engine,  which  is  ad- 
mitted to  the  cylinder  through  an  auxiliary  valve  which  is  oper- 
ated by  a  starting  cam  on  the  cam  shaft.  By  this  mechanism, 
high  pressure  air  is  furnished  to  the  cylinder  during  a  portion  of 
the  working  stroke,  turning  it  over  on  the  first  few  revolu- 
tions as  a  common  air  engine.  As  soon  as  the  engine  picks  up 
speed,  the  starting  valves  are  thrown  out  of  operation,  and 
the  engine  proceeds  on  its  regular  working  cycle  with  the 
oil  fuel. 

When  used  for  marine  purposes  in  sizes  over  100  horse-power, 
where  it  is  not  possible  to  use  reverse  gears,  the  Diesel  engine 
whether  of  the  two  stroke  cycle  or  four  stroke  cycle  type  must 
be  made  reversible.  This  may  be  accomplished  by  either  of 
two  methods,  first,  by  changing  the  angular  position  of  the 
cams  in  regard  to  the  piston  position,  and  second  by  using  two 


GAS,  OIL  AND  STEAM  ENGINES  165 

sets  of  cams,  one  being  for  right  hand  rotation  and  the  other 
for  left  hand.  When  a  single  cam  is  used,  the  relation  of  the 
cam  shaft  on  which  the  oil  pump  cams  and  oil  valve  cams  are 
located,  is  advanced  or  retarded  in"  respect  to  the  crank  shaft 
by  means  of  sliding  the  two  spiral  gears  that  drive  the  cam 
shaft,  over  one  another,  in  a  direction  parallel  to  their  axes. 
The  spiral  gears  are  moved  back  and  forth  by  a  hand  controlled 
reverse  lever.  This  type  is  used  principally  on  the  two  stroke 
cycle  type  of  engine  as  there  are  not  so  many  factors  to  con- 
tend with  as  on  the  four  stroke  cycle. 

With  double  cams,  the  system  almost  invariably  used  with  the 
four  stroke  cycle  engine,  the  cams  may  be  mounted  either  on 
one  shaft,  or  the  ahead  cams  on  one  cam  shaft  and  the  reverse 
cams  on  another.  When  two  shafts  are  used  they  are  arranged 
so  that  either  set  of  cams  may  be  swung  under  the  valve  lifters 
by  swinging  the  shafts  in  a  radial  direction  by  brackets.  The 
single  type  of  cam  shaft  is  usually  moved  back  and  forth  in 
a  direction  parallel  to  its  axis,  the  ahead  cams  coming  under 
the  valve  lifts  at  one  position,  and  the  reverse  cams  at  the 
other.  In  the  four  stroke  cycle  Diesel  it  is  evident  that  not 
only  the  relations  of  the  oil  pump  and  oil  valves  must  be 
changed  in  respect  to  the  piston  position  but  the  relations  of 
the  air  inlet  and  exhaust  valves  must  be  changed  as  well.  This 
necessitates  double  cams  for  the  inlet  and  exhaust  valves  in 
order  to  reverse  rotation. 

Compressed  air  for  starting  and  injection  is  generally  supplied 
by  a  three  stage  air  compressor  or  a  compressor  in  which  the 
pressure  is  built  up  in  three  different  steps,  the  second  cylinder 
taking  the  air  from  the  discharge  of  the  first,  and  the  third 
cylinder  taking  the  air  from  the  second,"  and  compressing  it 
to  about  250  pounds  above  'the  compression  pressure  of  the  en- 
gine. Perfect  scavenging  is  possible  with  this  engine  because 
of  the  large  excess  of  air  supplied  during  the  suction  stroke 
and  the  period  of  injection.  On  the  marine  type  the  air  pumps 
and  water  circulating  pumps  occupy  about  the  same  amount  of 
space  as  the  condenser  and  circulating  pumps  of  a  steam  engine 
having  the  same  outputs.  In  a  recent  test  made  with  an  Atlas- 
Diesel  engine  it  was  found  that  11  per  cent  of  the  output  was 
lost  in  driving  the  air  pumps  or  more  than  50  per  cent  of  the 
total  loss  by  friction  and  inipact. 

Unlike  the  ordinary  gasoline  engine  in  which  an  increase  of 
speed  increases  the  output  in  an  almost  direct  proportion,  the 
output  of  the  Diesel  engine  decreases  when  the  speed  rises 


Fig.  67.  Cross-Section  Through  the  Working  Cylinders  of  the  M.  S. 
Monte  Penado  Two  Stroke  Cycle  Diesel  Engine.  From  the  Motor 
Ship,  London. 


GAS,  OIL  AND  STEAM  ENGINES  '          167 

beyond  a  certain  limit  due  to  imperfect  combustion  at  speeds 
much  over  350  revolutions  per  minute.  Because  of  this  fact  it 
has  been  practically  impossible  to  apply  the  type  to  automobile 
service  which  ordinarily  requires  a  speed  of  from  400  to  800 
revolutions  per  minute  under  ordinary  conditions.  In  addi- 
tion to  the  speed  limitations,  the  Diesel  engine  weighs  approxi- 
mately 70  pounds  per  horse-power  against  an  average  weight  of 
17  pounds  per  horse-power  with  the  ordinary  type  of  gasoline 
automobile  motor.  Of  course  these  objections  may  be  over- 
come in  time,  as  the  engine  is  only  in  its  infancy,  and  the  two 
stroke  cycle  Diesel  has  not  yet  been  fully  developed,  but  at 
the  present  time  it  does  not  seem  probable  that  this  engine  will 
ever  be  an  active  competitor  of  the  gasoline  automobile  motor, 
at  least  from  the  standpoint  of  flexibility. 

As  the  Diesel  engine  depends  entirely  upon  compression  for 
its  operation,  it  is  necessary  that  all  of  the  parts  such  as  the 
pistons,  valves,  etc.,  shall  be  perfectly  fitted  and  air  tight  under 
extremely  high  pressures.  The  careful  workmanship  required 
for  such  fitting  and  the  adjustments  make  the  Diesel  much 
more  expensive  to  build  than  the  ordinary  type  of  gas  engine, 
and  for  this  reason  the  first  cost  and  overhead  charges  cut  into 
the  fuel  item  to  a  considerable  extent.  A  description  of  the 
Diesel  engines  will  be  found  in  the  chapter  devoted  to  oil 
engines. 

(63)  Diesel  Engine  (Marine  Type). 

As  a  practical  example  of  a  Diesel  engine,  which  was  de- 
scribed in  Chapter  III,  we  will  give  a  brief  description  of  the 
two  850  horse-power  Diesel  engines  installed  in  the  cargo 
vessel  "M.  S.  Monte  Penedo,"  which  were  built  by  Sulzer 
Brothers  of  Wintherthur,  Switzerland.  We  are  indebted  to  the 
Motor  Ship,  London,  for  the  details. 

The  engines  are  of  the  two  stroke  cycle,  single  acting  type, 
with  four  working  cylinders,  a  double  acting  scavenging  pump 
cylinder,  and  a  three  stage  ignition  compressor  cylinder.  The 
bore  of  the  working  cylinders  is  18.8  inches,  and  the  stroke  27 
inches.  While  the  crank  case  is  of  the  enclosed  type,  there 
are  two  sets  of  covers  which  can  be  easily  removed  for  in- 
spection while  the  engine  is  running,  for  as  the  scavenging 
pump  performs  the  work  of  the  crank  case  of  the  ordinary  two 
stroke  cycle  engine  there  is  no  need  of  a  tight  case  to  retain 
the  compression. 

The  scavenging  pump  is  mounted  on  one  end  of  the  engine 


168  GAS,  OIL  AND  STEAM  ENGINES 


e 


Fig.    G8.     Cross-Section    Through    the    Air    Cylinders    of    the    Two    Stroke 
Diesel    Motors    on    the    M.    S.    Monte    Penado. 


GAS,  OIL  AND  STEAM  ENGINES  169 

and  is  driven  from  the  crank-shaft,  the  cross-head  of  the  pump 
forming  one  piece  with  the  piston  of  the  low  pressure  cylinder 
of  the  injection  air  cylinder.  All  of  the  compressor  stages  are 
water  cooled  and  fitted  with  automatic  valves.  The  double  act- 
ing scavenging  pump  has  a  piston  valve  driven  by  a  link  mo- 
tion for  reversing  it  when  the  engine  is  reversed.  The  air 
enters  the  pump  through  the  top  valve  chamber  from  a  pipe 
leading  into  the  engine  room.  The  air  discharges  a  pressure 
of  about  3  pounds  per  square  inch  in  a  header  that  passes  in 
front  of  all  four  working  cylinders.  By  means  of  a  valve  the 
air  entering  the  low  pressure  stage  of  the  compressor  can  be 
taken  either  from  the  atmosphere  or  from  the  discharge  of  the 
scavenging  pump;  taking  the  air  from  the  latter  allows  of  a 
greater  weight  of  air  taken  by  the  compressor  and  consequently 
a  higher  compression  for  use  in  emergencies. 

As  in  the  ordinary  type  of  two  stroke  cycle  engine,  two  in- 
dependent sets  of  exhaust  ports  are  used,  one  set  being  for  the 
scavenging  air  and  the  other  for  the  exhaust  gases,  both  sets 
being  at  the  end  of  the  stroke  as  usual.  The  air  inlet  ports  are 
divided  into  two  groups,  however,  one  group  being  controlled 
by  the  piston  of  the  working  cylinder,  and  the  other  group  by 
an  independent  piston  valve  driven  from  the  cam-shaft.  Both 
sets  of  ports  connect  with  the  main  scavenging  air  header.  By 
means  of  the  valve  controlled  ports  it  is  possible  to  admit 
scavenging  air  even  after  the  other  ports  are  closed  by  the 
piston,  which  greatly  increases  the  scavenging  effect.  With 
the  air  at  3  pounds  pressure  the  air  from  the  valve  controlled 
ports  throw  the  scavenging  air  to  the  top  of  the  cylinder  even 
after  the  exhaust  ports  are  closed.  This  valve  is  provided  with 
a  reverse  mechanism.  A  single  cam  is  used  for  operating  the 
fuel  inlet  valve  and  the  air  starting  valve,  and  the  reversal  of 
the  engine  is  obtained  by  turning  the  cam  shaft  through  a  small 
angle  relative  to  the  crank-shaft,  which  of  course  also  reverses 
the  lead  of  the  fuel  valve.  Starting  is  accomplished  by  com- 
pressed air,  with  the  air  valve  lever  on  the  cam,  and  the  fuel 
valve  lever  off.  After  turning  through  a  few  revolutions,  the 
air  valve  levers  are  raised,  and  the  fuel  levers  dropped  back  on 
the  cams  which  results  in  the  engine  taking  up  its  regular  cycle, 

By  moving  the  tappet  rod  of  the  fuel  valve  out  of  or  into 
a  vertical  position,  the  time  of  the  fuel  valve  opening  is  reg- 
ulated and  the  amount  of  air  is  controlled.  This  movement  is 
normally  performed  by  a  compressed  air  motor,  but  in  an  emer- 
gency hand  wheels  mey  be  used. 


170  GAS,  OIL  AND  STEAM  ENGINES 

One  of  these  serves  to  rotate  the  camshaft  through  the  re- 
quired angle  in  order  to  set  the  cams  in  the  positions  for  astern 
or  ahead  running  and  also  reverses  the  link  motion  of  the 
scavenging  pump  valve  by  the  rotation  of  shaft,  as  mentioned 
above.  The  other  auxiliary  motor  operates  the  fuel  and  starting 
air  valves  by  moving  the  small  spindle  longitudinally  to  bring 
the  tappet  lever  of  the  air  valve  about  the  required  cam  for 
ahead  or  reverse  and  also  lifts  this  or  the  fuel  valve  tappet  rod 
off  its  cam,  according  as  it  is  desired  to  run  on  fuel  or  air. 

The  spindle  on  which  the  valve  levers  are  pivoted  is  in  two 
parts,  divided  at  the  center.  This  is  to  allow  two  of  the  cyl- 
inders to  run  on  air  whilst  the  other  two  are  running  on  fuel, 
and,  as  can  be  seen  from  the  dial  where  the  pointer  indicates 
the  position,  in  starting  up,  whether  astern  or  ahead,  first  two 
cylinders  are  put  on  air,  then  four  on  air,  next  two  on  air  and 
two  on  fuel,  and  finally  all  four  on  fuel.  This  allows  very 
rapid  attainment  of  full  speed. 

The  amount  of  fuel  entering  each  cylinder  can  be  regulated 
separately  by  small  hand  wheels. 

Below  the  fuel  pumps  are  arranged  three  auxiliary  pumps, 
two  of  these  being  oil  pumps  for  the  oil  circulation,  whilst  the 
other  is  of  the  piston  cooling  water.  On  the  left  of  the  en- 
gine and  driven  in  a  similar  manner  from  the  cross-head  by 
links  are  three  other  pumps,  one  for  the  circulating  water  and 
the  other  for  the  general  water  supply  of  the  ship. 

Lubrication  for  the  cylinders  is  furnished  by  8  small  pumps, 
just  above  the  water  pumps,  two  oil  pumps  being  provided  for 
each  cylinder.  As  the  supply  pipe  is  divided  into  two  parts, 
the  oil  reaches  the  cylinder  at  four  points  in  its  circumference. 
Four  oil  pumps  are  provided  for  the  air  compressor. 

Four  steel  columns  are  provided  for  the  support  of  each  cyl- 
inder in  addition  to  the  cast  iron  frame  of  the  base,  and  by 
this  means  the  explosion  stresses  are  transmitted  directly  to 
the  bed  plate.  The  cast  iron  columns  provide  guide  surfaces 
for  the  cross-head  shoes.  The  guides  are  all  water  cooled. 

(64)  The  M.A.N.  Diesel  Engine. 

The  Maschinenfabrik  Augsburg-Niirnburg,  G.  A.,  a  German 
firm  have  built  some  remarkably  large  Diesel  engines  both  of 
the  vertical  and  horizontal  types.  The  peculiar  merits  of  the 
horizontal  type  of  Diesel  engine  of  which  the  M.A.N.  company 
are  pioneers  are  still  open  to  discussion  at  present,  but  there 
is  no  doubt  but  what  this  type  will  be  the  ultimate  form  of 


GAS,  OIL  AND  STEAM  ENGINES 


171 


vary  large   engines  when   certain   alterations   are   made   in   the 
design. 

In  Fig.  69  is  shown  a  2,000  brake-horse-power  horizontal 
M.A.N.  Diesel  engine  of  the  four  stroke  cycle  type  which  is 
installed  at  the  Halle  Municipal  Electricity  Works,  Halle,  Ger- 


Fig.    69.     Horizontal    M.    A.    N.    Diesel    Engine    at    the    Halle    Municipal 

Plant. 


Fig.    70.     High    Speed    Mirlees-Diesel    Engine. 

many.  It  is  of  the  double  acting  type  with  twin-tandem  cyl- 
inders giving  four  working  impulses  per  revolution.  This  en- 
gine was  installed  in  addition  to  the  six  producer  gas  engines 
already  in  place  to  take  the  peak  load  of  the  station  at  different 
times  during  the  day,  the  gas  engines  meeting  the  normal, 
steady  demand. 


172 


GAS,  OIL  AND  STEAM  ENGINES 


This  firm  has  built  many  thousands  of  the  vertical  type  of 
Diesel  engine  of  all  sizes,  and  has  recently  installed  13  engines 
of  4,500  brake  horse-power  for  operating  the  Kreff  tramways. 
The  company  is  now  building  cylinders  giving  outputs  of  from 
1,200  to  1,500  brake  horse-power  per  cylinder,  giving  outputs  of 
from  5,000  to  6,000  horse-power  in  tandem  twin  type  engines. 
As  will  be  seen  from  the  cut,  the  horizontal  Diesel  engine  is 
remarkably  free  from  complicated  valve  gear. 

(65)  Mirlees-Diesel  Engines. 

The  Mirlees-Diesel  engine  is  built  by  the  English  firm,  Mir- 
lees,  Bickerton  and  Day  both  for  stationary  and  marine  service. 


Fig.  71.     Mirlees-Diesels  at  Dundalk. 

A  generating  plant  consisting  of  two,  200  horse-power  Mirlees 
engines  direct  co'nnected  to  Siemens  generators  has  been  in- 
stalled in  the  municipal  plant  at  Dundalk  as  shown  by  Fig.  71. 
On  test  these  units  consumed  0.647  pounds  of  oil  per  horse- 
power at  full  load  and  0.704  pounds  per  horse-power  at  half 
load  with  a  regulation  of  3.24  per  cent  from  full  load  to  no 
load.  All  of  the  engines  built  by  this  firm  are  of  the  four 
stroke  cycle  type. 

(66)  Willans-Diesel  Engines. 

The  Willans-Diesel  engines  built  by  the  Willans  and  Robinson 
Company  of  Rugby,  England,  are  in  sizes  up  to  400  brake  horse- 


GAS,  OIL  AND  STEAM  ENGINES 


173 


power,  and  run  at  speeds  up  to  250  revolutions  per  minute. 
They  are  all  of  the  four  stroke  cycle  type  and  are  applied  prin- 
cipally to  the  driving  of  electric  generators.  The  cut  shows 
one  of  the  four,  280  horse-power  units  supplied  to  the  Alranza 
Company  and  the  Rosario  Nitrate  Works  in  South  America. 
Unlike  the  Mirlees  engine,  the  Willans  has  an  individual 
frame  for  each  cylinder  as  in  steam  engine  practice.  Like  the 
steam  engine  frame,  the  bottom  is  left  open  for  the  inspection 
of  the  connecting  rod  ends  and  the  main  bearings  which  is  a 
most  desirable  feature.  The  air  compressor  and  pumps  are 
arranged  in  a  most  compact  form  at  the  left  end  of  the  crank- 


Fig.  72.     Willans  Vertical  Diesel   Engine. 

shaft  from  which  the  pipes  may  be  seen  issuing  to  the  four  cyl- 
inders. The  valves  and  over  head  gear  are  of  the  conventional 
type,  which,  with  the  exception  of  a  few  minor  details  are  the 
same  as  those  on  the  recently  developed  Sulzer-Diesel.  The 
individual  grouping  of  the  cylinder  units  has  many  desirable 
features  and  should,  we  believe,  be  more  extensively  copied. 

(67)  Installation  and  Consumption  of  Diesel  Plant. 

An  English  gas-electric  station  was  completed  at  Egham, 
England,  that  is  a  good  example  of  the  changes  that  have  been 
made  recently  in  the  electricity  supply  abroad,  with  Diesel 
power. 


174 


GAS,  OIL  AND  STEAM  ENGINES 


The  generating  plant  comprises  two  94  K.  W.  Diesel  en- 
gines built  by  Mirrless,  Bickerton  and  Day,  direct  connected 
to  single  phase  alternators  generating  at  2,000  volts.  The 
exciters  are  direct  connected  to  the  main  shaft,  and  the 
plant  is  capable  of  generating  an  overload  of  10  per  cent  for 
two  hours.  Space  has  been  left  for  the  installation  of  two 
more  units  of  a  larger  size. 

The  following  fuel  consumption  was  guaranteed  for  a  load 
of  unity  power  factor,  and  the  official  tests  show  slightly  bet- 
ter figures  than  the  guarantee. 

Full   load    0.68  Ib.  oil  per  K.  W.  H. 

Three-quarter   load 0.72  Ib.  oil  per  K.  W.  H. 

Half  load   0.79  Ib.  oil  per  K.  W.  H. 

Quarter  load 1.15  Ib.  oil  per  K.  W.  H. 


Cross-Section    Through    Egham,    England    Municipal    Plant. 

Particular  attention  has  been  given  to  the  water  supply  for 
the  jackets  of  the  engines;  the  circulation  being  by  two  elec- 
trically driven,  direct  connected  centrifugal  pumps,  one  of 
which  is  a  spare.  A  Little  Company's  cooler  has  been  installed, 
which  consists  of  a  horizontal  cylindrical  chamber,  the  lower 
part  of  which  contains  water.  In  the  tank  are  arranged  a 
number  of  concentric  metal  cylinders  spaced  about  ^-inch 
apart,  and  in  several  sections,  that  are  carried  on  a  slowly 
revolving  shaft,  driven  from  the  fan  shaft.  The  cylinders  are 
all  of  the  same  length,  and  are  open  at  both  ends. 

The  lower  half  of  the  cylinders  dips  into  the  water  in  the 
casing,  and  as  they  revolve,  a  thin  film  of  water  on  each  side 
of  the  plate  is  carried  into  the  upper  portion  of  the  casing 
where  it  meets  a  blast  of  cold  air  from  the  fan.  The  fan  is 
driven  from  the  circulating  pumps,  and  passes  the  air  through 


GAS,  OIL  AND  STEAM  ENGINES  175 

the  chamber  in  a  direction  opposite  to  that  of  the  water,  baffles 
being  placed  so  that  correct  circulation  is  maintained. 

The  small  loss  is  made  up  by  connecting  the  ball  cock  in 
the  tanks  with  another  tank  charged  from  the  works  well  by 
means  of  a  self-starting  rotary  pump,  electrically  driven.  Very 
little  power  is  required  for  the  pumps  and  cooler.  Fuel  oil  is 
stored  in  a  tank  outside  the  building,  the  oil  being  supplied 
to  the  tanks  from  an  oil  wagon  by  means  of  a  small  hand  pump. 

Oil  is  taken  from  the  tanks  and  forced  into  the  engine  room 
by  a  rotary  pump,  from  which  it  enters  two  graduated  tanks 
located  in  the  roof  of  the  station.  The  graduations  on  the 
tanks  allow  the  consumption  of  oil  to  be  carefully  recorded 
by  alternately  filling  and  emptying  the  two  auxiliary  fuel  tanks. 

The  entire  building  is  electrically  heated,  and  the  kitchen  of 
the  flat  above  the  station  is  equipped  with  an  electric  cook- 
ing-stove for  the  use  of  one  of  the  engineers  who  make  it  his 
residence. 

DIESEL  HORSE-POWER   FORMULA 

P.  A.  Holliday,  in  the  Engineer,  derives  a  new  formula  for 
computing  the  horse-power  of  the  four  stroke  cycle,  single- 
acting  engine.  For  each  horse-power  developed  by  these  en- 
gines about  21,000  cubic  inches  of  displacement  is  necessary, 
per  minute. 

D  =  Cylinder  bore  in  inches. 
S  =  Stroke   in   inches. 

M.P.S.  =  Mean  piston   speed   in  feet  per   minute. 
R  =  Ration  of  stroke  to  bore. 
N  =  Revolutions    per    minute,    then 

V  B.H.P.  X  222.0 
D  = 


M.P.S. 

6  M.P.S. 

Knowing  the  value  of  D,       N  — 


S 

For  high  speed,  low  ratio  (R),  four  stroke  cycle  engines, 
approximately  22,000  cubic  inches  displacement  per  minute  is 
required. 

V  2,330    B.H.P. 
D  = 


M.P.S. 

In   both   formulae,   the   air   compressor   for   fuel   injection   is 
Included. 


176  GAS,  OIL  AND  STEAM  ENGINES 

(32)  Semi-Diesel  Type  Engine. 

In  the  "Semi-Diesel"  Type  Engine  the  oil  is  injected  into 
the  cylinder  at  the  point  of  greatest  compression  in  the  same 
manner  as  in  the  Diesel  engine,  and  like  the  Diesel  it  compresses 
only  pure  air.  In  regard  to  the  compression  pressure,  however, 
it  stands  midway  between  the  pressure  of  the  Diesel  engine  and 
that  of  the  ordinary  "aspirating"  type  oil  engine,  as  the  com- 
pression averages  about  150  pounds  per  square  inch.  While 
this  is  a  much  higher  pressure  than  that  carried  by  the  ordinary 
kerosene  engine  which  compresses  a  mixture  of  kerosene  vapor 
and  air,  it  is  not  sufficiently  high  to  ignite  the  oil  spray  by  the 
increase  in  temperature  due  to  the  compression,  but  ignites  the 
charge  by  means  of  a  red  hot  bulb  or  plate  placed  in  the  com- 
bustion chamber. 

This  type  of  engine  is  built  both  in  the  two  stroke  and  four 
stroke  cycle  types,  the  events  occurring  in  the  same  order  as 
in  the  two  stroke  and  four  stroke  Diesel  types,  that  is,  pure  air 
is  drawn  into  the  cylinder  on  the  suction  stroke  (four  stroke 
cycle)  or  is  forced  in  at  the  beginning  of  the  compression  stroke 
(two  stroke  cycle),  and  is  compressed  in  the  combustion  cham- 
ber. At  the  end  of  the  compression  stroke,  the  fuel  is  injected 
against  the  red  hot  bulb  or  plate  by  which  the  charge  is  ignited. 
Expansion  follows  on  the  working  stroke  after  the  fuel  is  cut 
off,  and  release  occurs  at  the  end  of  the  stroke. 

Fuel  oil  is  supplied  to  the  spray  nozzles  by  a  governor  con- 
trolled pump  having  a  variable  stroke  or  by  compressed  air 
as  in  the  Diesel  engine,  making  the  supply  of  fire  proportional 
to  the  load.  A  separate  pump  is  generally  supplied  for  each 
cylinder,  which  is  capable  of  developing  a  pressure  of  about 
400  pounds  per  square  inch.  Several  of  the  Semi-Diesel  type 
engines  have  water  sprayed  into  the  cylinder  for  the  purpose  of 
cooling  the  cylinder  and  piston,  and  as  an  aid  in  the  combus- 
tion. This  water  spray  increases  the  output  of  a  given  size 
cylinder  by  the  amount  of  the  steam  formed  by  the  heat  of  the 
cylinder  and  piston  walls,  and  by  the  increased  rate  of  combus- 
tion. The  amount  of  water  supplied  to  the  cylinder  is  equal, 
approximately  to  the  amount  of  fuel  oil.  The  water  connection 
is  made  in  the  air  intake  pipe  so  that  the  water  spray  and  the 
intake  air  are  drawn  into  the  cylinder  at  the  same  time. 

There  is  very  little  difference  in  the  efficiency  of  the  Diesel 
and  Semi-Diesel  in  favor  of  the  true  Diesel  type  for  both 
have  accomplished  records  of  a  brake  horse-power  hour  on  .45 
pound  of  crude  oil  in  units  of  the  same  capacity.  Neglecting 


GAS,  OIL  AND  STEAM  ENGINES  177 

the  question  of  efficiency  the  Semi-Diesel  has  many  advantages 
which  are  due  principally  to  the  differences  in  compression 
pressures.  Valve  and  piston  perfection  in  regard  to  leakage  is 
not  as  essential  with  the  semi-type  as  with  the  Diesel,  as  the 
former  is  not  dependent  on  compression  for  its  ignition.  This 
means  that  the  Semi-Diesel  has  a  lower  first  cost  and  a  lower 
maintenance  expense.  Its  low  compression  pressure  makes 
starting  possible  without  the  use  of  compressed  air  with  engines 
of  a  considerable  horse-power.  As  the  explosion  pressure  is 
much  lower  than  with  the  Diesel  type  there  is  less  strain  on 
the  working  parts  and  lubrication  is  much  more  easily  per- 
formed. 

Compared  with  the  ordinary  type  of  kerosene  engine  the  Semi- 
Diesel  is  much  more  positive  in  its  action  as  the  oil  is  sure  to 
ignite  when  sprayed  on  the  hot  surface  of  the  bulb  or  plate 
when  under  the  comparatively  high  compression.  In  the  engine 
where  the  air  is  mixed  with  the  vaporized  fuel  before  it  is  drawn 
into  the  cylinder,  it  is  difficult  to  obtain  perfect  combustion  be- 
cause of  the  uncertain  mixtures  obtained  on  varying  loads  by 
the  throttling  method  of  governing.  At  light  loads  the  only 
difficulty  encountered  with  the  Semi-Diesel  type  is  that  of 
keeping  the  igniting  surface  hot  enough  to  fire  all  of  the 
charges. 

In  the  majority  of  cases  the  two  stroke  cycle  type  of  Semi- 
Diesel  engines  compress  the  scavenging  air  in  the  crank  cham- 
ber in  the  same  way  that  a  two  stroke  cycle  gasoline  motor 
performs  the  initial  compression,  although  there  are  several 
makes  that  compress  the  air  in  an  enlarged  portion  of  the  cyl- 
inder bore  by  what  is  known  as  a  "trunk"  piston.  This  initial 
compression  determines  the  speed  of  the  engine,  the  pressure 
limiting  the  time  in  which  the  air  traverses  the  cylinder  bore 
and  sweeps  out  the  burnt  gases  of  the  previous  explosion. 

(68)  De  La  Vergne  Oil  Engines. 

Two  types  of  four  stroke  cycle  oil  engines  are  built  by  the 
De  La  Vergne  Machine  "Company,  which  differ  principally  in 
the  method  and  period  of  injecting  the  fuel  into  the  cylinder. 
While  both  types  compress  only  pure  air  in  the  working  cylin- 
der, the  oil  is  injected  in  a  heated  vaporizer  during  the  suction 
stroke  in  the  smaller  engine  (type  HA),  and  is  injected  directly 
into  the  combustion  chamber  of  the  larger  engine  (type  FH) 
at  the  point  of  greatest  compression.  This  fuel  timing  classi- 


GAS,  OIL  AND  STEAM  ENGINES 


179 


fies  the  type  FH  as  a  semi-Diesel,  while  type  HA  comes  under 
the  head  of  that  class  of  engines  known  as  aspirators. 

Semi-Diesel  (Type  FH) 

During  the  suction  stroke,  air  is  drawn  into  the  cylinder 
through  the  inlet  valve  located  on  the  top  of  the  cylinder  head, 
and  on  the  return,  or  compression  stroke,  the  air  is  compressed 


i I 

76-b.     Cross-Section  of  Type  F  H,  De  La  Vergne  Oil  Engine. 

to  about  300  pounds  per  square  inch  in  the  combustion  cham- 
ber. The  compression  heats  the  air  to  a  high  temperature 
which  is  still  further  increased  by  contact  with  the  hot  walls 
of  a  cast  iron  vaporizer  D,  shown  by  Fig.  76-b.  At  the  com- 
pletion of  the  compression,  the  fuel  is  injected  in  a  highly 
atomized  state  by  compressed  air  through  the  spray  nozzle  F, 
the  spray  being  thrown  into  the  vaporizer. 

The  vapor  formed  by  the  contact  of  the  spray  with  the  walls 


180  GAS,  OIL  AND  STEAM  ENGINES 

of  the  vaporizer  mixes  with  the  compressed  air  in  the  com- 
bustion chamber  and  is  ignited  at  the  instant  of  fuel  admission 
by  the  combined  temperatures  of  the  vaporizer  and  compres- 
sion pressure. 

As  the  fuel  is  not  injected  until  the  proper  instant  for  igni- 
tion, it  is  possible  to  obtain  a  relatively  high  compression 
without  danger  of  the  charge  preigniting.  The  oil  is  supplied 
to  the  nozzle  by  a  fuel  pump  under  pressure.  The  atomizing 
air  takes  the  oil  at  pump  pressure  and  performs  the  actual 
injection.  Details  of  the  spray  valve  are  shown  by  Fig.  76, 
in  which  the  oil  and  air  are  entered  at  a  pressure  of  about 
600  poun.ds  per  square  inch. 


. 


Fig.    76.     De    La   Vergne    Spray   Nozzle. 

The  air  and  oil  enter  the  nozzle  at  opposite  sides  of  the 
cylinder  B  which  fits  snugly  into  the  valve  body  A.  As  the 
air  and  oil  proceed  side  by  side  along  the  ^outside  of  B,  they 
are  forced  to  pass  through  a  series  of  chambers  connected 
by  a  system  of  fine  diagonal  channels  on  the  surface  of  B 
which  results  in  a  very  fine  subdivision  and  intimate  mixture. 
The  charge  is  admitted  to  the  cylinder  by  a  sort  of  needle 
valve  about  one-half  inch  in  diameter  which  is  provided  with 
a  spring  that  holds  it  closed  on  its  seat  as  shown  by  C,  in 
Fig.  76.  The  needle  is  so  constructed  that  it  may  be  readily 
removed  at  any  time  for  inspection.  The  spray  valve  is  located 
on  the  right  hand  side  of  the  valve  chamber  directly  opposite 


GAS,  OIL  AND  STEAM  ENGINES 


181 


the  vaporizer  and  is  operated  by  an  independent  cam  on  the 
camshaft. 

The    vaporizer    consists    of    an    iron    thimble    having    ribs 
on    the    inside    to    increase    the    radiating    surface.     In    start- 


Fig.    76-c.      De    La   Vergne   Governor    and    Fuel    Pump. 

ing,  the  vaporizer  is  heated  for  a  few  moments  until  it  reaches 
the  temperature  necessary  for  vaporizing  the  fuel,  but  after 
the  engine  is  running,  the  blast  lamp  is  removed  and  the  tem- 
perature is  maintained  by  the  heat  generated  by  the  com- 


182  GAS,  OIL  AND  STEAM  ENGINES 

bustion  of  the  successive  charges.  Since  the  fuel  is  ignited 
at  the  instant  that  it  makes  contact  with  the  vaporizer,  it  is 
possible  to  accurately  adjust  the  point  of  ignition  by  adjusting 
the  position  of  the  fuel  cam  on  the  camshaft. 

Air  for  spraying  the  fuel  is  supplied  by  a  two  stage  air 
compressor  that  is  driven  from  the  crankshaft  by  an  eccen- 
tric. The  air  compressed  by  the  first  stage  is  stored  in  tanks 
at  about  150  pounds  pressure  for  starting  the  engine.  The 
second  stage  compresses  the  air  to  about  600  pounds  pressure, 
but  is  correspondingly  small  in  volumetric  capacity  since  it 
handles  only  enough  air  to  spray  the  oil  which  amounts  to 
about  2  per  cent  of  the  cylinder  volume.  A  governor  con- 
trolled butterfly  valve  in  the  air  intake  pipe  regulates  the 
amount  of  air  taken  in  on  the  second  stage  to  suit  the  vary- 
ing charges  of  oil  injected  at  each  load. 

In  starting  by  compressed  air,  a  quick  opening  lever  oper- 
ated valve  on  the  cylinder  head  is  used  to  admit  air  from  the 
tanks  to  turn  the  engine  over  until  the  first  explosion  takes 
place.  If  the  vaporizer  is  sufficiently  heated  by  the  torch, 
the  explosion  occurs  during  the  first  revolution  of  the  crank 
shaft.  At  a  point  about  85  per  cent  of  the  expansion  stroke, 
the  exhaust  valve  is  opened,  and  the  products  of  combustion 
are  expelled  into  the  atmosphere.  When  starting,  the  com- 
pression may  be  relieved  by  shifting  the  starting  lever  from 
the  exhaust  cam  to  the  auxiliary  starting  cam  provided  for 
that  purpose. 

Speed  regulation  is  affected  by  a  Hartung  governor,  driven 
from  the  camshaft,  which  actuates  the  oil  supply  pump 
through  levers  by  shifting  the  point  of  contact  between  the 
pump  levers  and  its  actuating  cam.  This  lengthens  or  shortens 
the  stroke  of  the  pump  in  accordance  with  the  requirements 
of  the  loa'd.  The  type  FH  engines  are  built  in  both  single 
and  twin  cylinders  ranging  from  90  to  180  horse-power  in 
the  single  cylinder  type  to  360  horse-power  in  the  twin. 

Since  the  fuel  injection  of  the  smaller  engine  type  HA  differs 
from  that  just  described,  it  will  be  described  separately  in 
the  following  section. 

The  De  La  Vergne  Oil  Engine  (Type  HA) 

In  the  small   four  stroke  cycle   De  La  Vergne   Oil   Engine, 

the  fuel  is  injected  into  a  heated  vaporizer  during  the  suction 

stroke  in  such  a  way  that  the  vapor  and  intake  air  do  not  form 

a   mixture   in   the   cylinder   proper.      On    the    return    stroke    of 


GAS,  OIL  AND  STEAM  ENGINES  183 

the  piston,  the  compression  of  the  pure  air  takes  place  which 
forces  the  air  into  the  vaporizer  and  into  intimate  contact 
with  the  oil  vapor.  This  forms  an  explosive  mixture  which 
ignites  and  forces  the  piston  outwardly  on  the  working  stroke. 
The  release  and  scavenging  are  performed  in  a  similar  man- 
ner to  that  of  a  four  stroke  cycle  gas  engine.  Both  the  inlet 
and  exhaust  valves  are  of  the  mechanically  operated  poppet 
type,  and  as  both  the  inlet  and  exhaust  gases  pass  through 
the  same  passage,  the  entering  air  i»  heated  to  a  comparatively 
high  temperature. 

The  injection  pump  receives  the  fuel  from  a  constant  level 
stand  pipe  or  tank,  located  near  the  engine  and  injects  the 
fuel  into  the  vaporizer  through  a  spray  nozzle.  The  vaporizer 
is  a  bulb  shaped  vessel  that  is  connected  with  the  cylinder 
through  a  short  post  and  really  forms  a  part  of  the  combus- 
tion chamber.  Since  no  water  jacket  surrounds  the  vaporizer, 
it  remains  at  a  high  temperature  and  vaporizes  the  oil  at  the 
instant  of  its  injection.  Because  of  the  residual  gases  remain- 
ing in  the  chamber,  ignition  does  not  occur  until  air  is  forced 
through  the  passage  by  the  compression.  The  air  inlet  valve 
and  the  fuel  injection  valve  are  opened  at  the  same  instant  by 
a  cam  lever  that  also  operates  the  pump. 

On  the  compression  stroke,  the  air  which  is  at  a  pressure 
of  approximately  75  pounds  per  square  inch  enters  the  vapor- 
izer, and  ignition  occurs,  partly  because  of  the  increased  heat 
due  to  'the  compression  and  partly  because  of  the  supply  of 
additional  oxygen.  Internal  ribs  provided  in  the  vaporizer 
greatly  increase  the  heat  radiating  surface  and  add  to  the 
thoroughness  with  which  the  atomized  oil  is  vaporized.  Since 
no  mixture  of  air  and  fuel  takes  place  in  the  cylinder  proper, 
sudden  changes  in  the  load  do  not  affect  the  ignition  of  the 
charge  as  the  heated  surfaces  are  surrounded  with  compara- 
tively rich  gas  under  all  conditions. 

Before  the  engine  is  started,  the  vaporizing  chamber  is  heated 
to  a  dull  red  heat  by  means  of  a  blast  torch  in  order  to  vaporize 
the  oil  for  the  first  stroke.  As  soon  as  the  engine  is  running, 
the  lamp  is  cut  out  and  the  temperature  is  maintained  by 
the  heat  of  the  successive  explosions.  The  combustion  at- 
tained by  this  method  is  very  complete  even  with  the  heaviest 
fuels,  and  whatever  carbon  deposit  is  formed  occurs  in  the 
vaporizer  from  which  it  is  easily  removed.  The  contracted 
opening  of  the  vaporizer  passage  effectually  prevents  the  solid 
matter  from  working  in  the  bore  or  valves. 


184  GAS,  OIL  AND  STEAM  ENGINES 

A  Porter-type  fly  ball  governor  maintains  a  constant  speed 
at  varying  loads  by  regulating  the  quantity  of  fuel  supply  to 
the"  vaporizer,  the  air  intake  remaining  constant.  A  by-pass 
valve,  controlled  by  the  governor  divides  the  oil  supplied  by 
the  pump,  into  two  branches,  one  of  which  leads  to  the 
spray  nozzle  and  the  other  to  the  supply  tank.  In  the  case 
where  all  of  the  oil  is  not  supplied  to  the  vaporizer  because 
of  a  light  load,  the  by-pass  valve  will  return  the  surplus  to 
the  tank,  thus  maintaining  a  constant  pressure  at  the  spray 
nozzle. 

When  operating  under  ordinary  loads,  the  governor  opens 
'  only  the  small  inside  valve  which  regulates  the  amount  of  oil 
injected  into  the  vaporizer.  But  should  the  engine  speed  up, 
due  to  a  sudden  change  in  the  load,  the  governor  will  not 
only  open  the  small  valve  but  also  the  large  concentric  valve, 
in  which  case  all  of  the  oil  will  return  to  the  tank.  The  mak- 
ers guarantee  the  following  speed  variation  limits  under  the 
different  loads. 

Ordinary  Variation 2*/2  per  cent. 

Full  load  to  one-quarter  load 4      per  cent. 

Full    load    to    no    load 5       per  cent. 

(69)  Operating  Costs  of  the  Semi-Diesel  Type. 

As  the  semi-Diesel  type  engine  will  operate  successfully  on 
the  lowest  grades  of  crude  oils,  with  an  efficiency  that  compares 
favorably  with  the  true  Diesel  type,  the  operating  expenses  are 
very  much  lower  than  with  the  gas  or  gasoline  engine.  With 
the  same  fuels,  the  semi-Diesel  will  show  greater  net  saving 
than  the  Diesel  with  a  low  load  factor,  as  the  fuel  saving  is 
not  eaten  up  by  the  high  first  cost,  and  overhead  charges  of 
the  true  Diesel.  Western  trude  oils  with  a  specific  gravity  of 
.960  (16°  Beaume)  are  being  used  daily  with  this  type  of  en- 
gine while  nearly  every  builder  of  the  semi-Diesel  type  will 
guarantee  results  with  oils  up  to  18°  Beaume  (.948  Specific 
Gravity).  Fuel  of  this  grade  will  cost  anywhere  from  \l/2  cents 
to  3^2  cents  per  gallon  in  tank  car  lots,  depending  on  the  dis- 
tance of  the  engine  from  the  wells  or  refinery. 

With  fuel  oil  weighing  7l/2  pounds  per  gallon,  an  engine 
consuming  .65  pounds  per  horse-power  hour  (a  usual  guarantee) 
at  full  load,  the  cost  of  a  horse-power  hour  delivered  at  the 
shaft  will  be  .26  cent  with  fuel  at  3  cents  per  gallon.  This 
the  lowest  fuel  expense  of  any  prime  mover  even  with  steam  or 
gas  units  of  great  power.  In  a  twenty-four  hour  test  of  a 


GAS,  OIL  AND  STEAM  ENGINES  185 

De  La  Vergne  oil  engine  running  on  19°  Beaume  oil,  the  con- 
sumption was  considerably  below  the  figure  assumed  above, 
being  .508  pounds  per  horse-power  hour.  Even  the  engine 
was  exceeded  in  a  test  made  on  a  175  horse-power  engine 
by  Dr.  Waldo,  which  gave  a  consumption  of  .347  pounds  of  oil 
per  horse-power  hour  with  oil  of  .86  Specific  Gravity. 

The  following  is  a  tabulation  of  reports  received  by  the 
De  La  Vergne  Machine  Company  from  the  Snead  Iron  Works, 
giving  the  cost  of  power  at  their  plant  under  actual  working 
conditions  extending  over  a  period  of  twenty-four  months. 
The  plant  consisted  of  a  17  X  27^  inch  De  La  Vergne  semi- 
Diesel  type  engine  of  180  horse-power  rated  capacity,  the 
load  factor  being  54.2  per  cent.  The  total  power  produced 
during  the  record  was  552,217  horse-power  hours,  with  a  work- 
ing period  of  588  days.  Fuel  =  28.8°  Beaume  —  7.35  pounds 
per  gallon. 

TABULATION 

Items  Total  Cost     Cost  per     Cost  per 

K.W.  Hour  H.P.  Hour 

Fuel    Oil,    38,211    gallons $859.75  $.00232  $.00155 

Lubricating    Oil    228.72  .00061  .00041 

Miscellaneous   Stores  and   Repairs...  123.20  .00032  .00022 

Labor  and  Attendance    1361.42  .00368  .00246 

Total    $.00693    $.00464 

Fuel  oil  used  =  .761  pounds  per  K.  W.  hour  =  .508  pounds 
per  horse-power  hour.  Computing  from  the  load  factor  of 
54.2  per  cent,  the  cost  of  power  produced  under  the  above 
conditions  would  be  $9.30  per  horse-power  year,  or  $13.98  per 
kilowatt  year.  This  result  is  obtained  by  assuming  that  the 
horse-power  hours  would  be  increased  from  552,217  to  1,077,354, 
or  in  proportion  to  the  actual  load  factor,  the  period,  of  course 
being  the  same  in  both  cases. 

(70)  Elyria  Semi-Diesel  Type. 

A  type  of  semi-Diesel  type  oil  engine  has  been  recently 
developed  by  the  Elyria  Gas  Power  Co.,  Elyria,  O.,  that 
presents  many  features  of  interest.  It  operates  on  the  two 
stroke  cycle  principle,  and  with  the  exception  of  the  spray 
nozzle  has  no  valves  in  the  working  cylinder.  The  prin- 
ciple of  the  semi-Diesel  type  cycle  as  distinguished  from  the 
true  Diesel  engine,  was  described  in  Chapter  III,  as  having 


186 


GAS,  OIL  AND  STEAM  ENGINES 


the  following  characteristics.  (1)  Fuel  injection.  (2)  Medium 
compression  pressure.  (3)  Hot  plate  ignition.  (4)  An  ef- 
ficiency approximating  that  of  the  true  Diesel  type. 

It  is  claimed  that  the  change  from  the  ordinary  four  stroke 
cycle  Diesel  cycle  has  been  accomplished  with  practically  no 
loss  of  thermal  efficiency,  and  that  the  elimination  of  the  many 
moving  parts  of  that  type  has  done  away  with  many  of  the 
operating  difficulties.  By  the  introduction  of  a  false  piston 
end  and  an  unjacketed  cylinder  head,  the  loss  of  efficiency  due 
to  the  lower  compression  is  compensated  by  the  reduction  of 


Fig.    77.     Working    Cylinder   of    Elyria    Oil    Engine. 

heat  loss  to  the  jacket  water.  Because  of  the  high  temper- 
ature it  is  possible  to  burn  the  heaviest  fuels  with  a  maximum 
pressure  not  exceeding  400  pounds  per  square  inch,  and  with- 
out trouble  due  to  missed  ignition  at  light  loads.  With  a  given 
cylinder  capacity  this  heating  effect  has  increased  the  output 
about  75  per  cent.  The  loss  due  to  the  friction  of  the  scaveng- 
ing apparatus  causes  a  fuel  consumption  of  approximately  10 
percent  more  than  a  standard  four  stroke  Diesel. 

Unlike  the  Diesel,  this  engine  automatically  controls  the 
quantity  of  injection  air  admitted  to  the  cylinder  at  different 
loads,  the  air  corresponding  with  the  amount  of  fuel  injected. 
This  is  in  marked  contrast  with  the  Diesel  engine  which  admits 
a  constant  volume  of  air  at  all  loads.  In  place  of  the  usual 


GAS,  OIL  AND  STEAM  ENGINES 


187 


crank-case  compression  of  the  scavenging  air  met  with  in  the 
ordinary  two  stroke  cycle  engine,  the  initial  compression  in 
the  Elyria  engine  is  performed  by  a  "differential  piston"  which 
acts  in  an  enlarged  'portion  of  the  cylinder  bore.  This  con- 
struction increases  the  volumetric  efficiency  from  70  percent, 
in  the  case  of  the  marine  type,  to  well  over  90  percent,  and  it 
also  does  away  with  the  bad  effect  of  the  compression  on  the 
lubrication  of  the  main  crank  shaft  bearings. 

The  working  piston  and  differential  piston  as  shown  by  Fig. 
77  is  separate  castings  fastened  together  by  four  studs,  and  the 


Fig.    78.     Compressor   Cylinder   of    Elyria    Oil    Engine. 


piston  pin  is  carried  by  the  differential  piston  which  acts  as  a 
cross-head,  taking  all  of  the  sjde  thrust  from  the  main  piston. 
The  working  piston  is  easily  taken  from  the  cylinder  by  remov- 
ing the  cylinder  head  and  the  four  nuts  that  fasten  it  to  the 
differential  piston  casting.  The  displacement  of  the  differential 
piston  is  approximately  1.9  times  the  displacement  of  the  work 
ing  piston  which  is  more  than  enough  for  thoroughly  scaveng 
ing  the  cylinder  and  supplying  air  for  combustion.  The  air 
suction  is  controlled  by  a, piston  valve  which  eliminates  much 
of  the  loss  encountered  in  the  marine  type  of  two  stroke  cycle. 
In  the  figure  may  be  seen  the  separate  or  auxiliary  piston 
head  which  is  bolted  to  the  piston  proper,  a  construction  that 
greatly  increases  the  working  temperature,  and  allows  a  sym- 
metrical form  of  piston.  By  removing  the  cap  over  the  inlet 


188  GAS,  OIL  AND  STEAM  ENGINES 

port, -it  is  possible  to  inspect  the  condition  of  the  six  piston 
rings  with  removing  the  piston  from  the  cylinder.  Because  of 
the  clean  burning  of  .the  fuel  lubrication,  is  easily  effected  by 
the  force  pump  which  supplies  oil  at  three  points  around  the 
cylinder  wall. 

Three  stages  of  compression  are  employed  for  providing  the 
air  for  fuel  injection,  the  first  stage  being  accomplished  by  the 
differential  piston,  and  the  remaining  two  stages  by  a  separate 
air  pump  driven  by  an  eccentric  from  the  crankshaft.  This 
cylinder  also  supplies  the  air  for  starting  the  engine,  the  air 
being  taken  from  the  second  stage  and  piped  to  the  storage 
tank.  The  suction  of  the  second  stage  pump  which  receives  its 
air  from  the  differential  pump  (first  stage)  is  controlled  auto- 
matically so  that  it  is  possible  to  keep  the  supply  tank  at  any 
desired  pressure  regardless  of  the  pressure  or  amount  of  air 
used  for  the  fuel  injection.  Air  from  the  tank  (at  approximately 
200  pounds  pressure)  is  piped  to  the  suction  side  of  the  third 
stage  air  pump.  In  this  suction  line  is  a  valve,  controlled  by 
the  governor,  which  regulates  the  amount  of  air  admitted  to 
the  injection  nozzle,  and  also  the  amount.  This  pressure  at 
the  nozzle  will  vary  from  500  pounds  per  square  inch  to  1000 
pounds  depending  on  the  load  and  the  nature  of  the  fuel.  The 
high  pressure  air  travels  directly  from  the  pump  to  the  fuel 
valve  casing,  and  -is  equipped  with  a  safety  valve  and  pressure 
gauge. 

The  fuel  pump  is  driven  by  a  Rites  Inertia  Governor  located 
in  the  fly-wheel  which  varies  the  stroke  of  the  pqmp  plunger 
and  gives  a  correct  proportion  of  fuel  to  the  load.  This  type 
of  governor  has  been  extensively  used  on  high  speed  engines 
and  is  exceeding  accurate.  The  fuel  pump  may  be  disconnected 
from  the  governor  drive,  and  operated  by  hand  when  it  is  nec- 
essary to  provide  fuel  for  starting.  The  spray  or  injection  valve 
is  operated  by  a  cam,  which  lifts  the  valve  at  the  proper  mo- 
ment in  a  very  simple  manner.  The  valve  proper  is  made  of 
a  single  piece  of  steel  with  openings  of  ample  size,  so  that 
there  is  no  danger  of  clogging  with  the  heaviest  fuels.  As  the 
valve  only  lifts  1/16  of  an  inch,  the  amount  of  work  required 
to  operate  the  valve  is  very  small. 

Starting  is  accomplished  by  spraying  cold  gasoline  into  the 
cylinder  through  the  fuel  valve  in  the  same  manner  that  the 
heavier  oil  is  fed  during  operation,  and  the  ignition  is  performed 
by  a  high  tension  coil  and  batteries.  No  spark  time  device  is 
used,  so  that  a  continuous  shower  of  sparks  is  thrown  into 


GAS,  OIL  AND  STEAM  ENGINES  189 

the  mixture  during  the  starting  period.  Within  a  minute  after 
the  engine  is  started,  the  ignition  switch  may  be  opened,  the 
gasoline  cut  off,  and  the  heavy  oil.  turned  on  for  continuous 
running  on  full  load.  Starting  by  an  electric  spark  avoids  the 
inconvenience  and  danger  of  torch  starting  with  a  retort. 

Cooling  water  is  admitted  around  the  compressor  cylinder 
from  which  point  it  goes  to  the  working  cylinder,  and  is 
there  discharged.  Less  water  is  required  for  this  type  of  engine 
than  for  the  ordinary  gasoline  engine,  for  with  the  water  en- 
tering at  60°F,  only  3  gallons  per  horse-power  hour  is  used. 
With  fuel  oil  weighing  7.33  pounds  per  gallon  the  makers 
claim  a  fuel  consumption  of  .65  pounds  per  horse-power  at  the 
rated  load.  The  amount  of  cylinder  oil  used  does  not  exceed  1 
pint  per  100  horse-power  hours,  while  the  loss  of  the  bearing 
oil  is  extremely  small  because  of  the  return  system. 

(71)  Remington  Oil  Engine. 

The  Remington  Oil  Engine  is  a  vertical  oil  engine  operating 
on  the  three  port,  two  stroke  cycle,  and  is  an  oil  engine  in  the 
strict  meaning  of  the  word,  the  oil  consumed  being  introduced 
into  the  combustion  chamber  as  a  liquid  and  gasified  within  this 
chamber. 

The  method  of  gasifying  and  igniting  the  charge  of  oil  in 
the  Remington  Oil  Engine  is  unique.  Only  clean  air  un- 
mixed with  any  charge,  is  taken  into  the  crankcase.  This  air 
is  afterwards  passed  up  into  the  cylinder  and  compressed  until 
its  temperature  has  raised  to  a  point  high  enough  to  vaporize 
the  oil  which  is  injected  into  it.  The  charge  of  oil  is  then 
atomized  into  this  hot  compressed  air  and  turns  immediately 
into  a  vapor,  which  finds  itself  well  mixed  with  the  charge  of 
air,  comes  in  contact  with  a  firing  pin  recessed  in  the  head, 
ignite  and  burns.  This  method  of  having  the  oil  well  gasified 
and  mixed  with  air  before  ignition  begins,  prevents  the  forma- 
tion of  carbon  which  is  formed  when  oil  not  well  gasified  and 
mixed  with  air  comes  suddenly  MI  contact  with  very  hot 
surfaces. 

This  perfect  system  of  gasifying  the  oil  has  the  effect  not 
only  of  preventing  the  formation  of  carbon  in  the  cylinder,  but 
also  of  increasing  the  mean  effective  pressure  and  therefore  de- 
creasing the  amount  of  fuel  necessary  for  doing  a  certain 
amount  of  work.  The  engine  passes  through  its  cycle  of  oper- 
ations smoothly,  and  does  not  have  to  be  constructed  with  ex- 
cessive weight. 


390  GAS,  OIL  AND  STEAM  ENGINES 


Fig.    79.     Cross-Section    of    Remington    Oil    Engine. 


GAS,  OIL  AND  STEAM  ENGINES  191 

The  Remington  Engine  is  of  the  valveless  type,  delivering  a 
power  impulse  in  each  cylinder  for  each  revolution  of  flywheel. 
The  gases  are  moved  in  and  out  of  the  cylinder  through  ports 
uncovered  by  the  movement  of  the  piston,  which  itself  performs 
also  the  function  of  a  pump. 

On  the  up  stroke  of  the  piston  a  partial  vacuum  is  created 
in  the  enclosed  crankcase,  causing  air  to  rush  in  when  the  bot- 
tom of  the  piston  uncovers  the  inlet  port  seen  directly  under 
the  exhaust  port  (23),  Fig.  79.  On  the  next  down  stroke  this 
air  is  compressed  in  the  crankcase  to  about  four  or  five  pounds 
pressure  per  square  inch.  Meanwhile  the  mixture  of  oil  vapor 
and  air  already  in  the  cylinder  is  burning  and  expanding. 
When  the  piston  approaches  the  end  of  its  down  stroke,  it 
uncovers  the  exhaust  port  (23),  permitting  the  burnt  charge 
to  escape,  until  its  pressure  reaches  that  of  the  atmosphere. 


Fig.    80.     Remington    Spray    Nozzle. 

Directly  afterward  the  transfer  port  on  the  opposite  side  of 
the  cylinder  is  uncovered  by  the  piston,  thereby  allowing  a 
portion  of  the  air  compressed  in  the  crankcase  to  rush  into 
the  cylinder,  where  it  is  deflected  upwards  by  the  shape  of  the 
top  of  the  piston  and  caused  to  fill  the  cylinder,  thereby  expell- 
ing the  remainder  of  the  burnt  charge.  The  piston  now  starts 
upward,  compressing  the  fresh  charge  of  air  into  the  hot 
cylinder  head.  Near  the  end  of  the  stroke,  a  small  oil  pump, 
mounted  on  the  crankcase  and  controlled  by  the  governor,  in- 
jects the  proper  amount  of  oil  through  the  nozzle  (13),  into 
the  compressed  and  heated  air. 

This  oil  is  atomized  in  a  vertical  direction  through  a  hole 
near  the  end  of  the  nozzle.  It  is  therefore  vaporized  and  gasi- 
fied before  there  is  a  possibility  of  its  reaching  the  cylinder 
walls. 

The  spray  of  oil  is  ignited  by  the  nickel  steel  plug  (12), 
which  is  kept  red  hot  by  the  explosions  because  the  iron  walls 
surrounding  it  are  protected  from  radiation  by  the  hood  (11). 


192 


GAS,  OIL  AND  STEAM  ENGINES 


By  the  burning  of  the  oil  spray  in  the  air  the  pressure  is  grad- 
ually increased  and  the  piston  forced  downward,  this  being  the 
power  or  impulse  stroke.  Near  the  end  of  the  down  stroke, 
the ''exhaust  port  is  again  uncovered  and  the  burnt  gases  dis- 
charged. 


Fig.  81.     Fuel  Pump  and  Mechanism  of  Remington  Oil  Engine. 

The  operations  above  described  take  place  in  the  cylinder 
and  crankcase  with  every  revolution.  Each  upstroke  of  the 
piston  draws  fresh  air  into  the  crankcase  and  compresses  the 
air  transferred  to  the  cylinder.  Each  down  stroke  is  a  power 
stroke,  and  at  the  same  time  compresses  the  air  in  the  crank- 
case  preparatory  to  transferring  it  to  the  cylinder  by  its  own 
pressure  at  the  end  of  the  stroke. 

The  same  volume  of  air  enters  the  cylinder  under  all  condi- 
tions, and  the  power  is  regulated  by  modifying  the  stroke  of  the 


GAS,  OIL  AND  STEAM  ENGINES 


193 


oil  pump,  which  may  be  done  by  hand  or  automatically  by  the 
governor  in  the  flywheel.  A  separate  fuel  pump  is  provided 
for  each  cylinder  when  multiple  cylinders  are  used,  making  it 
absolutely  certain  that  each  cylinder  shall  receive  the  same 
amount  of  fuel  for  a  position  of  the  control  lever. 

When  starting  the  engine,  the  hollow  cast  iron  prong  rising 
from  the  cylinder  head  is  heated  by  a  kerosene  torch,  and  when 
hot,  a  single  charge  of  oil  is  admitted  to  the  cylinder  by  work- 
ing the  hand  pump.  The  flywheel  is  now  turned  backward, 
thereby  compressing  the  charge  which  ignites  the  fuel  before 
the  piston  reaches  the  highest  position.  After  being  started 
the  engine,  the  torch  may  be  extinguished. 


Fig.    82.     Two    Cylinder    Remington    Oil     Engine    Direct    Connected    to 

Dynamo. 

The  governor  is  of  the  centrifugal  type.  It  has  an  L-shaped 
weight,  pivoted  to  the  piece  attached  to  the  flywheel.  As  the 
engine  speed  increases,  the  weight  tends  to  swing  outward 
toward  the  flywheel  rim,  and  thereby  moves  the  arm  attached  to 
it  so  as  to  shift  the  cam  along  the  crankshaft  toward  the  left. 

This  cam  turns  with  the  shaft,  and  operates  the  kerosene 
oil  pump.  According  to  the  position  of  the  cam  on  the  shaft, 
it  will  impart  to  the  pump  plunger  a  long  or  a  short  stroke, 
thereby  injecting  more  or  less  oil  into  the  cylinder.  The  lever 
pivoted  on  the  bracket  moves  with  the  cam  and  is  used  for 


194  GAS,  OIL  AND  STEAM  ENGINES 

controlling  the  engine's  speed  by  hand.  To  stop  the  engine 
the  handle  of  the  lever  is  pulled  towards  the  flywheel,  thereby 
interrupting  the  pump  action  altogether. 

The  handle  of  the  control  lever  can  be  fitted  with  an  ad- 
justable speed  regulator  when  required.  This  device  is  for 
use  on  marine  engines  to  enable  the  operator  to  slow  down 
the  engine.  The  speed  regulator  does  not  interfere  with  the 
action  of  the  governor  but  acts  in  conjunction  with  it.  What- 
ever the  speed  of  the  engine  may  be,  it  is  under  the  control  of 
the  governor.  The  engine  can  be  controlled  from  the  pilot 
house  if  such  an  arrangement  is  desirable. 

The  fuel  pump  is  made  of  bronze.  The  valves  are  made 
of  bronze  and  are  designed  with  very  large  areas.  The  plunger 
is  made  of  tool  steel.  A  bronze  cup  strainer  is  attached  to  the 
lower  end  of  the  pump  to  prevent  sediment  or  foreign  matter 
from  reaching  the  pump  valves.  As  a  result  of  the  care  used 
in  its  construction,  the  fuel  pump  is  not  only  very  sensitive  in 
measuring  the  oil  required  by  the  governor,  but  is  also  very 
strong  and  durable. 

The  nozzle  through  which  the  fuel  is  atomized  into  the 
cylinder  is  thoroughly  water  jacketed  to  prevent  the  forma- 
tion of  carbon  within  the  nozzle.  It  is  so  constructed  that  the 
water  jacket  spaces  and  fuel  spaces  can  be  opened  for  inspection. 

Lubrication  of  all  the  important  bearing  joints  is  effected  by 
a  mechanical  force  feed  oiler,  pressure  feed  oiler  or  by  gravity 
sight  feed  oilers,  depending  upon  the  service  for  which  the  en- 
gine is  designed.  Oil  is  fed  in  this  manner  to  the  piston,  the 
main  bearings  and  the  crankpin  bearings.  The  oil  for  the 
crankpin  is  dropped  from  a  tube  into  an  internally  flanged  ring 
attached  to  the  crank  by  which  it  is  carried  by  centrifugal  force 
to  a  hole  drilled  diagonally  through  the  crank  and  crankpin  to 
the  centre  of  the  bearing.  This  insures  that  all  the  oil  intended 
for  the  crankpin  shall  reach  it.  This  feature,  as  well  as  the 
use  of  the  sight  feed  oiler  itself,  is  in  line  with  the  best  modern 
high  speed  engine  practice,  and  is  an  important  factor  in  the 
reliability  of  the  engine. 


CHAPTER  VIII 
IGNITION  SYSTEMS 

(73)  Principles  of  Ignition. 

It  is  the  purpose  of  the  ignition  system  to  raise  a  small 
portion  of  the  mixture  to  the  combustion  temperature,  or  the 
temperature  at  which  the  air  and  fuel  will  start  to  enter  into 
chemical  combination.  When  combustion  is  once  started  in 
a  compressed  combustible  gas  it  will  spread  throughout  the 
mass  no  matter  how  small  the  original  portion  inflamed.  The 
rate  at  which  the  flame  spreads  through  the  combustion  cham- 
ber depends  upon  the  compression  pressure,  the  richness  of 
the  mixture,  the  nature  of  the  fuel  and  upon  the  number  of 
points  at  which  it  is  ignited. 

In  practice  perfect  ignition  is  seldom  realized.  This  is  due 
not  only  to  the  ignition  system  itself  but  to  poor  mixture 
proportions,  imperfect  vaporizing  of  the  fuel,  and  low  com- 
pression; all  of  which  tend  to  a  slow  burning  mixture  with  the 
attendant  losses. 

The  best  ignition  system  will  be  that  which  will  cause  the 
ignition  to  occur  invariably  at  the  point  of  highest  compres- 
sion and  which  will  supply  ample  heat  to  start  the  process  of 
combustion  with  a  cold  cylinder,  imperfect  mixtures,  and  low 
compressions.  An  efficient  and  reliable  ignition  system  is  with- 
out a  doubt  the  most  important  unit  in  the  construction  of  a 
gas  engine.  As  ignition  systems  have  improved  and  become 
more  reliable,  so  has  the  gas  engine  become  more  widely  used 
and  appreciated,  and  in  almost  a  direct  proportion  to  these  im- 
provements. 

Many  ingenious  ignition  systems  have  been  proposed,  but 
only  two  of  these  have  met  with  any  degree  of  success  in 
practice;  i.  e.,  electrical  ignition  and  ignition  by  means  of  the 
hot  tube. 

Sponge  platinum  has  the  peculiar  property  of  igniting  jets 
of  hydrogen  gas,  or  hydrocarbons,  without  the  aid  of  heat; 
this  is  due  to  the  condensing  effect  of  the  platinum  on  these 
gases. 

195 


196  GAS,  OIL  AND  STEAM  ENGINES 

It  was  proposed  to  ignite  the  gaseous  charge  of  the  gas  en- 
gine by  means  of  the  platinum  sponge  (catalytic  ignition)  but 
the  system  proved  a  failure  because  of  the  clogging  of  the 
pores  in  the  sponge  by  fine  particles  of  soot. 

Dr.  Otto  employed  an  open  flame  which  was  introduced  into 
the  mixture  by  means  of  a  slide  valve.  This  met  with  only  a 
fair  measure  of  success. 

Cerium,  Lanthum  and  several  other  rare  metals  cause  a 
considerable  spark  when  brought  into  contact  with  iron  or 
steel.  The  objection  to  this  method  was  the  expense  of  the 
Cerium  plugs  which  required  frequent  renewal. 

The  writer  remembers  a  quaint  attempt  at  firing  the  charge 
by  means  of  a  piece  of  flint  and  steel;  the  failure  of  this  is 
obvious. 

The  Diesel  Engine,  a  great  success  from  a  thermodynamic 
standpoint,  is  fired  by  means  of  the  heat  produced  by  the  com- 
pression of  air,  the  fuel  being  sprayed  into  air  which  is  com- 
pressed to  several  hundred  pounds  pressure. 

Mr.  Victor  Lougheed  proposes  ignition  by  means  of  a  plati- 
num wire  rendered  incandescent  by  a  current  of  electricity. 
The  plan  sounds  feasible,  but  we  are  still  waiting  to  be  shown. 

Electric  ignition  is  applicable  to  all  classes  of  engines;  in 
fact  this  system  made  the  variable  speed  engine  as  used  on 
automobiles,  etc.,  a  possibility,  as  accurate  timing  with  the 
electric  spark  covers  the  range  from  the  lowest  possible  speed 
to  speeds  of  4,500  revolutions  per  minute  and  over. 

(74)  Advance  and  Retard. 

While  the  combustion  of  the  mixture  is  extremely  rapid 
under  favorable  conditions,  there  is,  nevertheless,  a  percep- 
tible lapse  between  the  instant  of  ignition  and  the  final  pres- 
sure established  by  the  heat  of  the  combustion.  For  this  rea- 
son it  is  necessary  that  ignition  should  be  started  a  certain 
length  of  time  before  the  pressure  is  required  if  we  are  to  ex- 
pect a  maximum  pressure  at  a  definite  point  in  the  stroke  of 
the  piston.  The  amount  by  which  the  time  of  ignition  precedes 
that  of  combustion  is  called  the  ADVANCE,  and  is  usually 
given  in  terms  of  angular  degrees  made  by  the  crank  in  travel- 
ing from  the  time  of  ignition  to  time  of  maximum  pressure. 
Since  the  pressure  is  always  required  at  the  extreme  end  of 
the  compression  stroke,  the  degree  of  advance  is  given  as 
the  angle  made  by  the  center  line  of  the  cylinder  with  the  center 
line  of  the  crank  at  the  instant  of  ignition.  Should  the  ad- 


GAS,  OIL  AND  STEAM  ENGINES  197 

vance  be  given  as  10°,  for  example,  it  is  meant  that  the  crank 
is  still  10°  from  completing  the  compression  when  ignition 
occurs. 

Owing  to  variations  in  the  richness  of  the  mixture,  and 
changes  in  the  compression  pressure,  due  to  throttling  the 
incoming  charge,  the  rate  of  inflammation  varies  from  time  to 
time  under  varying  loads.  To  keep  the  maximum  pressure  at 
a  given  point  under  these  conditions  it  is  necessary  to  vary 
the  point  of  ignition  to  correspond  with  the  increase  or  de- 
crease of  inflammation.  This  variation  of  advance  to  meet 
varying  loads  is  approximated  by  the  governor  in  some  engines, 
and  manually  in  others.  The  advance  of  an  automobile  is  an 
example  of  manual  ignition  control.  Should  the  point  of  igni- 
tion vary  from  the  theoretical  point  it  will  result  in  a  loss  of 
fuel  and  power,  and  for  this  reason  the  ignition  should  be 
under  at  least  an  approximate  control.  A  wide  variation  in 
engine  speed  has  a  very  considerable  effect  on  the  ignition 
point  as  there  is  less  time  in  which  to  burn  the  mixture'  at 
high  piston  speeds,  and  consequently  the  ignition  must  be 
further  advanced  to  insure  complete  combustion  at  the  end  of 
the  stroke.  This  fact  is  evident  to  those  who  have  driven  auto- 
mobiles. 

Should  the  ignition  occur  too  early,  so  that  combustion  is 
complete  before  the  piston  reaches  the  end  of  the  stroke,  there 
will  be  a  loss  of  power  due  to  the  tendency  of  the  pressure  to 
reverse  the  rotation  of  the  engine.  When  starting  an  engine, 
over-advanced  ignition  will  throw  the  crank  over  in  the 
reverse  direction  from  which  it  is  intended  to  go,  and  will  not 
only  prevent  the  engine  from  coming  up  to  speed  but  will  prove 
dangerous  to  the  operator. 

Due  to  the  effects  of  inertia  and  self  induction  in  several 
types  of  ignition  apparatus,  a  greater  advance  will  be  required 
than  that  demanded  by  the  combustion  rate  of  the  mixture. 
This  sluggishness  of  the  apparatus  in  responding  to  the  piston 
position  is  called  ignition  LAG.  The  total  advance  required 
to  have  the  combustion  complete  at  the  end  of  the  stroke  is 
equal  to  the  advance  required  by  the  burning  speed  plus  the 
ignition  lag.  Since  lag  is  principally  due  to  inertia  effects, 
it  is  much  greater  at  high  speeds  than  at  low,  and  it  therefore 
causes  an  additional  advance  at  high  speeds.  Causing  the  igni- 
tion to  occur  before  the  crank  reaches  the  upper  dead  center 
is  called  ADVANCED  IGNITION,  causing  it  to  occur  after 
the  piston  has  reached  the  upper  dead  center,  or  when  on  the 
outward  stroke,  is  called  RETARDED  IGNITION. 


198  GAS,  OIL  AND  STEAM  ENGINES 

Ignition  is  retarded  when  starting  an  engine  to  prevent  it 
from  taking  its  initial  turn  in  the  wrong  direction.  As  the 
combustion  takes  place  after  the-  compression,  with  the  piston 
moving  on  the  working  stroke,  in  retard,  it  is  impossible  for 
the  pressure,  to  force  the  piston  in  any  direction  but  the  right 
one.  -  Excessively  retarded  ignition  will  cause  a  power  loss  and 
will  also  cause  overheating  of  the  cylinder  and  valves  as  the 
combustion  is  slower. 

(75)  Preignition. 

Preignition  which  is  in  effect  the  same  as  over-advanced 
ignition  as  due  to  causes  within  the  cylinder  such  as  incandes- 
cent carbon  deposits-  or  thin  sharp  edges  in  the  cylinder  that 
have  become  incandescent  through  the  heat  of  the  successive 
explosions.  Preignition  is  very  objectionable  since  it  causes 
heavy  strains  on  the  engine  parts  and  causes  a  loss  of  power 
in  the  same  way  as .  over-advanced  ignition.  Any  condition 
that  causes  the  preigniting  of  the  charge  should  be  removed 
immediately. 

(76)  Misfiring. 

The  failure  of  the  ignition  apparatus  to  ignite  every  charge 
is  called  MISFIRING.  This  missing  not  only  causes  a  waste 
of  fuel  and  a  loss  of  power  but  it  also  causes  an  increased  strain 
on  the  engine  parts  because  of  the  violence  of  the  explosion 
following  the  missed  stroke.  The  heavy  explosion  is  due  to  the 
fact  that  the  stroke  following  the  "miss"  is  more  thoroughly 
scavenged  by  the  two  admissions  of  the  mixture  than  the  or- 
dinary working  stroke,  and  consequently  contains  a  more  active 
charge. 

(77)  Hot  Tube  Ignition. 

A  combustible  gas  may  be  ignited  by  bringing  it  into  contact 
with  surface  heated  to,  or  above  the  ignition  temperature.  It  is 
upon  this  principle  that  hot  tube  ignition  is  based. 

In  practice  this  surface  is  provided  by  the  bore  of  a  tube 
which  is  in  communication  with  the  charge  in  the  cylinder,  the 
outer  end  of  the  tube  being  closed  or  stopped  up.  Around  this 
tube  is  an  asbestos-lined  chimney  which  causes  the  flame  from 
the  Bunsen  burner  to  come  into  contact  with  the  tube  and  also 
prevents  draughts  of  air  from  chilling  it. 

A  Bunsen  burner  is  located  near  the  base  of  the  tube  and 
maintains  it  at  bright  red  heat.  The  gas  for  the  burner  is  sup- 


GAS,  OIL  AND  STEAM  ENGINES  199 

plied  from  a  source  external  to  the  engine.  When  the  fuel 
used  is  gasoline,  a  gasoline  burner  is  used,  which  is  fed  from 
a  small  supply  tank  located  five  or  six  feet  above  the  burner. 

During  the  admission  stroke,  the  hot  tube  is  filled  with  the 
non-combustible  gases  remaining  from  the  previous  explosion, 
therefore,  the  fresh  entering  gases  cannot  come  into  contact 
with  the  hot  walls  of  the  tube  and  cause  a  premature  explo- 
sion, before  the  charge  is  compressed. 

As  the  compression  of  the  new  charge  proceeds,  the  fresh 
gas  is  forced  farther  and  farther  into  the  tube  and  at  the 
highest  point  of  compression  it  has  penetrated  far  enough  to 
come  into  contact  with  the  hot  portion.  At  this  point  the 
explosion  occurs. 

The  tube  being  of  small  bore,  does  not  allow  of  the  burnt 
gases  mingling  with  the  fresh  within  the  tube;  the  waste  gases 
in  the  tube  acting  as  a  regulating  cushion.  The  distance  of 
travel  of  the  new  mixture  is  proportional  to  the  compression, 
hence  the  explosion  does  not  occur  until  a  certain  degree  of 
compression  is  attained. 

The  length  of  the  tube  required  for  a  given  engine  is  a  mat- 
ter of  experiment,  as  is  also  the  location  of  the  heated  portion. 
High  compression  naturally  forces  the  mixture  farther  into 
the  tube  than  low,  therefore  the  flame  should  come  into  con- 
tact with  the  tube  at  a  point  nearer  the  outer  end  with  high 
compression  than  with  a  low  compression. 

Shortening  the  tube  causes  advanced  ignition,  as  the  mixture 
reaches  the  heated  portion  sooner,  or  earlier  in  the  stroke, 
because  of  the  decreased  cushioning  effect  of  the  residue  gases 
in  the  tube. 

The  length  of  tube  and  location  of  maximum  heat  zone 
should  be  so  proportioned  that  combustion  will  take  place  at 
the  highest  compression.  Moving  flame  to  outer  end  of  the 
tube  retards  ignition.  Moving  the  flame  toward  the  cylinder 
advances  it. 

While  the  hot  tube  is  the  acme  of  simplicity  in  construction, 
it  is  not  the  easiest  thing  to  properly  adjust,  as  the  adjustment 
depends  on  compression,  temperature  of  the  tube,  and  the 
quality  of  the  mixture.  Any  of  these  variables  may  cause  im- 
proper firing. 

The  hot  tube  is  rather  an  expensive  type  of  ignition  with 
high  priced  fuel,  as  the  burner  consumes  a  considerable  amount 
of  gas,  and  is  burning  continuously  during  the  idle  strokes  as 
well  as  during  the  time  of  firing. 


200  GAS,  OIL  AND  STEAM  ENGINES 

It  is  practically  impossible  to  obtain  satisfactory  results  from 
a  hot  tube  on  an  engine  that  regulates  its  speed  by  varying  the 
mixture  or  compression,  as  engines  running  on  a  light  load 
will  not  have  sufficient  compression  to  cause  the  mixture  to 
come  into  contact  with  the  hot  surface,  the  engine  misfiring 
on  light  loads. 

The  tubes  are  made  of  porcelain,  nickel  steel  alloy,  or  com- 
mon gas  pipe,  and  are  of  various  diameters  and  lengths. 

All  of  these  materials  have  their  faults.  Porcelain  being 
very  brittle,  is  liable  to  breakage.  Gas  pipe  burns  out  and 
corrodes  rapidly.  Nickel  alloy  is  not  liable  to  breakage,  is  not 
so  susceptible  to  corrosion  as  iron,  but  is  far  from  being  a 
permanent  fixture. 

Timing  valves  are  a  feature  of  some  systems  of  hot  tube 
ignition,  which  correct  to  a  certain  extent  the  irregularity  of 
firing  of  the  plain  type  of  tube. 

The  timing  valve  is  introduced  in  the  passage  connecting  the 
cylinder  and  tube,  and  prevents  the  gas  in  the  cylinder  from 
coming  into  contact  with  the  heated  surface  until  ignition  is 
desired. 

The  valve  is  operated  by  means  of  mechanism  connecting  it 
with  the  crank  shaft.  It  is  evident  that  with  sufficient  com- 
pression in  the  cylinder,  the  time  of  ignition  can  be  obtained 
with  certainty. 

This  mechanism  is  rather  complicated,  and  subject  to  wear, 
and  the  advantage  gained  by  the  fixed  point  of  ignition  is  offset 
by  mechanical  complication  and  consequent  trouble. 

The  action  of  hot  tube  igniters  is  erratic  and  their  use  is  not 
advisable  unless  under  unusual  conditions.  The  open  flame  used 
in  heating  the  tube  is  a  constant  menace,  as  it  is  surrounded 
by  inflammable  vapors.  This  feature  alone  condemns  it  in  the 
eyes  of  the  insurance  underwriters;  in  many  places  the  use 
of  the  hot  tube  is  prohibited  both  by  the  underwriters  and 
city  ordinances. 

The  above  inherent  defects  of  hot  tubes  are  supplemented 
by  breakage,  "blowing,"  and  clogging  of  the  tube  or  passage 
with  soot  and  products  of  corrosion,  each  factor  of  which  will 
cause  misfiring. 

In  case  of  misfiring,  after  determining  that  the  tube  is  not 
broken  or  clogged  with  soot  or  dirt,  see  that  the  engine  is 
being  supplied  with  the  proper  mixture;  that  you  are  obtain- 
ing the  proper  compression;  and  that  the  Bunsen  burner  is  de- 
livering a  bright  blue  flame  on  the  tube  at  the  proper  point, 


GAS,  OIL  AND  STEAM  ENGINES  201 

Never  allow  the  burner  to  develop  a  yellow  sooty  flame.  A 
yellow  flame  indicates  that  insufficient  air  is  being  admitted 
to  the  burner.  Remember  that  an  overheated  tube  is  quickly 
destroyed,  and  will  cause  misfiring  as  surely  as  an  underheated 
tube.  Regulate  the  gas  supply  to  the  burner. 

A  small  leak  near  the  outer  end  of  the  tube  will  destroy  the 
cushioning  effect  of  the  burnt  gas,  and  hence  will  cause  pre- 
mature firing  of  the  charge.  Procure  a  new  tube. 
-  Many  engines  are  provided  with  a  sliding  burner  and  chim- 
ney which  allows  of  some  adjustment  of  the  flame  on  the  tube. 
In  cases  of  persistent  misfiring,  move  the  chimney  one  way  or 
the  other.  It  may  improve  the  ignition. 

(78)  Electrical  Ignition. 

Ignition  by  means  of  an  electric  spark  is  by  far  the  most 
satisfactory  method  as  it  makes  accurate  timing  and  prompt 
starting  possible.  It  is  the  most  reliable  of  all  systems  and 
is  easily  inspected  and  adjusted  by  anyone  having  even  a 
rudimentary  idea  of  electricity  or  the  gas  engine.  For  this 
reason  electric  ignition  is  used  on  practically  all  modern  en- 
gines (with  the  exception  of  the  Diesel  types).  The  spark  is 
caused  by  the  current  jumping  an  opening  or  gap  in  the  con- 
ducting path  of  the  current,  and  the  ignition  of  the  charge 
is  obtained  by  placing  this  cap  in  the  midst  of  the  combustible 
mixture  to  which  the  spark  communicates  its  heat. 

The  method  of  producing  the  spark  gap,  and  the  method 
by  which  the  current  is  forced  to  jump  the  gap,  divides  the 
electrical  ignition  system  into  two  principal  classes: 

(1)  The  MAKE  AND  BREAK,  or  LOW  TENSION  system. 

(2)  The  JUMP  SPARK  or  HIGH  TENSION  system. 

In  either  system  the  spark  is  produced  by  the  electrical  fric- 
tion of  the  current  passing  through  the  high  resistance  of  the 
gas  in  the  spark  gap.  The  incandescent  vapor  in  the  gap 
formed  by  this  increase  of  temperatures  causes  the  flash  that  is 
known  as  the  spark.  The  temperature  of  the  gap  depends 
principally  upon  the  current  flowing  through  it,  the  amount  of 
heat  developed  being  proportionat  to  the  square  of  the  current. 

There  is  of  course  a  practical  limit  to  the  amount  of  current 
used  in  the  ignition  apparatus  to  produce  spark  heat.  The 
limit  is  generally  set  by  considerations  of  the  life  of  the  bat- 
tery furnishing  the  current,  expense  of  generating  the  cur- 
rent, and  the  life  of  the  contact  points  between  which  the 
spark  occurs. 


202  GAS,  OIL  AND  STEAM  ENGINES 

The  heat  developed  by  an  electric  current  is  proportional  to 
the  amount  of  resistance  offered  to  its  flow  and  the  strength 
of  the  current  employed.  The  greater  the  resistance,  the  more 
heat  developed. 

The  resistance  of  copper  wire  (the  usual  conducting  path), 
being  very  low  causes  little  rise  in  temperature,  but  the  air  in 
the  opening  or  break  has  a  resistance  of  many  thousands  of 
times  the  resistance  of  the  copper;  hence  the  current  passing 
across  the  opening  spark  or  gap  raises  the  air  to  an  exceed- 
ingly high  temperature. 

With  a  comparatively  heavy-  current  flowing  across  the 
break,  the  temperature  developed  is  high  enough  to  boil  or 
vaporize  any  metal  in  contact  with  the  spark  or  flame,  render- 
ing the  metallic  vapors  incandescent.  With  sufficient  current,  the 
ends  of  the  wires  which  constitute  the  break  may  be  melted  away. 

For  the  successful  and  continuous  operation  of  the  engine 
it  is  imperative  that  ends  of  the  conducting  path  or  terminals 
be  made  of  a  metal  of  a  high  fusing  point  in  order  to  with- 
stand the  heat  of  the  spark  and  also  that  the  current  be 
kept  to  as  low  a  value  as  possible. 

In  actual  construction  the  spark  gap  terminals  are  generally 
made  of  platinum  or  platino-iridium,  or  an  alloy  of  high  fus- 
ing point.  Iron  is  sometimes  used,  but  deterioates  rapidly. 
Nickel  steel  lasts  longer  than  common  iron  or  steel  but  is  not 
as  durable  as  platinum  or  its  alloys. 

As  the  temperature  of  the  electric  spark  or  arc  is  approxi- 
mately 7,500°  F.,  and  the  ignition  temperature  of  an  ordinary 
rich  gas  at  70  Ibs.  compression  is  1,100°  F.,  it  is  evident  that  the 
quantity  of  current  for  ignition  may  be  kept  to  an  exceedingly 
low  value.  High  compression  increases  the  resistance  of  the 
spark  gap,  and  requires  higher  electrical  pressure  to  force  a 
given  current  across  a  gap  of  given  length. 

(79)  Sources  of  Current. 

The  electric  current  that  causes  the  ignition  spark  is  usually 
generated  or  supplied  by  one  of  the  three  following  methods: — 

1.  By  the  primary  battery  which  converts  the  chemical  en- 
ergy of  metal,  and  some  corroding  fluid,  into  electrical  energy, 
by  chemical  means. 

2.  By    the    magneto    or    dynamo    that    converts    mechanical 
work    or    energy    into    electrical    energy    through    the    method 
of  magnetic  induction. 

3.  By   the    storage    or    secondary   battery   which    acts   as    a 


GAS,  OIL  AND  STEAM  ENGINES  203 

reservoir  or  storage  tank  for  current  that  has  been  generated 
by  either  of  the  two  above  methods.  A  storage  battery  sim- 
ply returns  electrical  energy  that  has  been  expended  on  it  by 
an  external  generator.  A  storage  battery  does  not  really  gen- 
erate electricity  but  as  it  is  often  used  as  a  source  of  current 
for  an  ignition  system,  we  will  consider  it  as  a  generator. 

Current  producers  that  convert  chemical  or  mechanical  en- 
ergy into  electrical  energy  are  called  primary  generators,  and 
are  represented  by  the  primary  battery  and  dynamo.  The 
above  methods  are  used  for  generating  current  for  either  the 
high  or  low  tension  systems. 

Electricity  may  also  be  produced  by  friction,  but  as  such 
current  is  without  heat  value  it  is  not  used  for  ignition  pur- 
poses. Electricity  produced  by  friction  is  called  static  electricity. 

Primary  and  storage  batteries  always  deliver  a  direct  or 
continuous  current  of  electricity,  that  is  a  current  which  flows 
continually  in  one  direction.  Dynamos  are  usually  made  to 
furnish  a  direct  current,  but  can  be  built  to  deliver  either 
direct  or  alternating. 

Alternating  current,  unlike  the  continuous  current,  changes 
the  direction  of  its  flow  periodically;  flowing  first  in  one  direc- 
tion and  then  in  the  other,  the  flow  alternating  in  equal  periods 
of  time. 

Magnetos  being  a  special  form  of  dynamo  can  furnish  either 
class  of  current,  but  with  few  exceptions  are  built  for  generat- 
ing alternating  current. 

Either  current  may  be  used  for  ignition  purposes  for  either 
high  or  low  tension  systems. 

Alternating  current  has  several  advantages  not  possessed  by 
the  continuous  current,  when  used  for  ignition  purposes.  The 
principal  advantages  are: 

1.  Alternating  current  does  not  transfer  the  electrode  metal 
of  contact  points,   and   consequently   causes   less   trouble  with 
vibrators  and  "make"  and  "break"  igniters. 

2.  Magnetos    generating   alternating   current    are    less    com- 
plicated, have  fewer  parts  to  get  out  of  order,  and  are  cheaper 
to  keep  in  repair. 

3.  Alternating  current  is  not  liable  to  burn  out  spark  coils 
or  overheat  with  an  excessive  voltage. 

4.  Alternating  current  generators  can  be  used  at  any  speed 
without  the  use  of  governors. 

When  installing  an  ignition  system  give  due  consideration  to 
the  reliability  of  the  source  of  current.  The  gas  engine  is  no 


204 


GAS,  OIL  AND  STEAM  ENGINES 


43-a.  The  Esselbe  Rotary  Aero  Motor.  Four  Pistons  are  Contained 
in  the  Ring  Shaped  Cylinder  at  the  Left  Which  are  so  Connected 
with  Cranks  and  Gears  in  the  Gear  Box  that  the  Pistons  and  the 
Cylinder  Rotate  in  Opposite  Directions.  As  the  Pistons  Rotate 
they  also  Oscillate  Back  and  Forth  in  Regard  to  One  Another,  so 
that  the  Working  and  Compression  Strokes  are  Performed.  From 
Aero  London. 


GAS,  OIL  AND  STEAM  ENGINES  205 

more  reliable  than  its  source  of  current.     Failure  of  the  current 
means  the  failure  of  the  engine. 

(80)  Primary  Batteries. 

Current  is  produced  in  a  primary  battery  by  the  chemical 
action  of  a  fluid  known  as  an  ELECTROLYTE  upon  two  dis- 
similar metals  or  solids  known  as  the  electrodes.  One  of  the 
electrodes,  the  negative,  is  usually  made  of  zinc  which  is  more 
readily  attacked  by  the  electrolyte  than  the  positive  electrode. 
As  the  metal  of  the  negative  electrode  is  dissolved  and  passes 
into  the  solution  during  the  process  of  current  generation,  the 
electrolyte  is  also  exhausted.  The  production  of  current  is 
accompanied  by  the  liberation  of  hydrogen  gas  from  the  elec- 
trolyte from  which  it  is  displaced  by  the  zinc  taken  into  solu- 
tion. 

When  the  electrodes  are  immersed  in  the  electrolyte,  and 
the  outer  ends  of  the  electrodes  are  connected  with  a  wire,  a 
current  will  flow  from  the  positive  electrode  to  the  negative 
through  the  wire,  and  from  the  negative  to  the  positive  elec- 
trode through  the  fluid.  It  will  be  seen  that  to  complete  the 
circuit  between  the  electrodes  it  is  necessary  that  the  current 
flows  through  the  electrolyte. 

Electrical  energy  is  actually  generated  in  the  primary  bat- 
tery by  the  chemical  combustion  of  the  negative  electrode  in 
the  same  way  that  heat  energy  is  developed  by  the  burning 
of  a  fuel. 

By  connecting  the  binding  posts  of  the  electrodes  to  the 
two  wires  of  the  external  circuit,  a  current  will  flow  through 
the  circuit  as  long  as  the  electrodes  remain  undissolved,  or 
until  the  positive  electrode  is  covered  with  hydrogen  gas 
bubbles. 

.The  bubbles  of  gas  tend  to  insulate  the  positive  electrode 
from  the  electrolyte  or  fluid,  thus  breaking  the  circuit  through 
the*  fluid,  and  stopping  the  flow  of  current.  This  action  is 
known  as  polarization. 

When  a  battery  is  polarized,  the  only  remedy  is  to  discon- 
nect it  from  the  circuit  and  allow  it  to  rest  or  recuperate.  The 
greater  the  current  drawn  from  a  battery,  the  more  rapid  the 
polarization,  and  it  is  evident  that  if  the  battery  is  to  be  used 
for  long  periods,  polarization  must  be  eliminated,  or  the  cur- 
rent must  be  considerably  reduced  in  volume.  A  battery  that 
delivers  a  small  current  has  a  much  greater  capacity  in  am- 
pere hours  than  a  battery  that  has  a  higher  rate  of  discharge. 


206  GAS,  OIL  AND  STEAM  ENGINES 

The  greater  the  discharge  rate  the  longer  must  be  the  rest 
periods. 

A  battery  that  is  designed  for  continuous  service,  or  for  de- 
livering heavy  currents  of  long  duration,  is  called  a  closed- 
circuit  battery.  Polarization  is  eliminated  in  closed  circuit 
batteries  by  various  methods,  the  usual  methods  being  to  place 
some  substance  in  the  electrolyte  that  will  destroy  the  hydrogen 
film;  or  by  packing  some  solid  oxidizing  material  around  the 
positive  electrode  that  will  absorb  the  hydrogen;  or  by  making 
the  positive  electrode  of  some  material  that  will  destroy  the 
hydrogen  as  soon  as  it  is  developed. 

Batteries  that  are  capable  of  being  operated  only  for  short 
periods,  on  account  of  polarization,  are  called  open  circuit 
batteries.  Open  circuit  batteries  are  cheaper  and  more  simple 
than  closed  circuit  batteries.  For  ignition  purposes,  a  battery 
is  made  that  is  a  compromise  between  the  closed  and  open 
circuit  cells,  this  being  a  battery  in  which  the  polarization  is 
only  partially  suppressed.  As  the  demand  for  current  on  an 
ignition  battery  is  small  with  comparatively  long  rests  between 
contacts,  the  compromise  battery  answers  the  purpose  and  is 
fairly  cheap. 

All  primary  batteries  are  in  reality  wet  batteries,  for  the 
reason  that  it  would  be  impossible  to  cause  a  chemical  reac- 
tion and  a  current  with  a  dry  electrolyte.  The  action  of  dry 
and  wet  batteries  is  identical. 

There  are  many  types  of  wet  battery  in  use  for  various  pur- 
poses, but  few  of  them  are  adapted  for  gas  engine  ignition  be- 
cause of  a  tendency  to  polarize  or  because  of  the  cost  of  main- 
tenance. 

All  wet  batteries  are  not  suitable  for  portable  or  automobile 
engines  because  of  the  slopping  of  the  liquid  electrolyte  and  the 
danger  of  breaking  the  containing  jars.  Their  weight  and  bulj< 
is  also  a  drawback. 

If  the  electrolyte  or  the  electrodes  be  made  of  impure  ma- 
terial local  currents  will  be  generated.  These  currents  de- 
crease the  life  of  the  cell  without  producing  any  useful  current 
in  the  ignition  circuit.  Due  to  the  deteriorating  effects  of  the 
local  currents,  batteries  standing  idle  for  several  months  will 
often  be  found  to  be  completely  discharged  and  worthless 
without  having  done  any  useful  work.  In  the  better  grade  of 
cells  this  loss  is  reduced  to  a  minimum. 

A  type  of  wet  battery  using  a  solution  of  caustic  soda  for 
an  electrolyte,  and  having  zinc  and  copper  oxide  electrodes,  is 


GAS,  OIL  AND  STEAM  ENGINES  207 

extensively  used  for  stationary  ignition  purposes,  and  is  the 
most  satisfactory  type  of  wet  cell  for  continuous  work  with 
this  class  of  engine.  The  caustic  soda  battery  is  of  the 
CLOSED  circuit  type,  and  is  capable  of  furnishing  a  strong 
uniform  current  without  danger  of  polarization. 

The  hydrogen  bubbles  which  cause  polarization  are  oxidized 
or  eliminated  by  the  copper  oxide  electrode  as  soon  as  they  are 
formed.  The  hydrogen  combines  with  the  oxygen  of  the  cop- 
per oxide  forming  water. 

The  copper  oxide  is  gradually  reduced  to  metallic  copper  by 
the  reaction  with  the  hydrogen,  and  in  the.  course  of  time  re- 
quires renewal.  The  copper  oxide  element  is  rather  expensive 
and  cannot  be  obtained  as  readily  as  the  electrodes  used  in 
other  cells. 

It  will  be  noted  that  both  electrodes  are  consumed  in  the 
caustic  battery,  the  consumption  of  the  zinc  furnishing  the 
current,  and  the  reducing  of  the  oxide  furnishing  the  chemical 
energy  for  depolarizing  the  cell. 

(81)  Dry  Batteries. 

"Dry  batteries  are  by  far,  the  most  convenient  and  economical 
form  of  primary  battery  to  use,  for  there  is  no  fluid  to  slop 
and  leak,  the  first  cost  is  low,  the  output  is  large  for  the 
weight,  and  last  but  not  least,  the  cell  can  be  thrown  away 
when  exhausted  without  great  monetary  loss.  This  does  away 
with  the  expense  and  annoyance  of  changing  wet  cells,  a  factor 
that  will  be  appreciated  by  those  that  are  far  from  a  source 
of  chemical  supplies.  Since  the  advent  of  the  automobile  the 
use  of  dry  cells  has  extended  so  that  they  may  be  obtained 
in  almost  any  country  town  or  village. 

While  the  cell  is  not  dry,  strictly  speaking,  the  solution  is 
held  in  such  a  way  that  it  cannot  slop  around  in  the  cell  nor 
leak  out  of  the  seal.  The  only  fault  of  a  dry  cell  is  its  ten- 
dency to  deteriorate  with  age  because  of  the  constant  contact 
of  the  electrolyte  with  the  electrodes. 

The  negative  electrode  of  the  dry  cell  (zinc)  is  in  the  form 
of  a  cup  which  serves  as  a  containing  vessel  for  the  electro- 
lyte and  the  depolarizer. 

The  electrolyte  is  usually  composed  of  a  solution  of  am- 
monium chloride,  with  a  small  percentage  of  zinc  sulphate,  this 
fluid  being  held  by  some  absorbent  material  such  as  blotting 
paper,  or  paper  pulp. 

The  electrolyte  is  applied  to  the  electrodes  by  means  of  the 


208  GAS,  OIL  AND  STEAM  ENGINES 

saturated  blotting  paper,  which  is  also  used  to  line  the  zinc 
container,  thus  providing  insulation  between  the  electrodes. 

A  rod  of  solid  carbon  which  forms  the  positive  electrode  is 
placed  in  the  center  of  the  container,  and  the  space  between 
the  rod  and  the  zinc  is  packed  solidly  with  granulated  carbon, 
the  blotting  paper  lining  preventing  contact  of  the  zinc  with 
the  carbon. 

Pulverized  manganese  dioxide  is  mixed  with  the  granulated 
carbon  for  a  depolarizer. 

After  the  zinc  container  is  filled  with  the  electrolyte  and 
pulverized  carbon,  the  top  of  the  container  is  closed  hermetic- 


Brookes    Four    Cylinder    Gasoline     Engine    Direct    Connected    to    Dynamo. 

ally  by  means  of  sealing  wax.  Granulated  carbon  is  used  for 
it  presents  a  large  surface  to  the  electrolyte,  reduces  the 
internal  resistance  of  the. cell,  and  therefore  increases  the  cur- 
rent output  of  the  battery. 

As  soon  as  the  battery  starts  generating  current,  polarization 
begins,  with  the  liberation  of  hydrogen  gas.  If  the  cell  is 
discharged  at  a  high  rate,  the  manganese  dioxide  will  be  un- 
able to  absorb  all  of  the  gas,  and  consequently  pressure  will 
be  erected  within  the  cell.  The  greater  the  rate  of  discharge, 
the  greater  will  be  the  amount  of  hydrogen  set  free,  and  the 
higher  the  pressure. 

If  a  short  circuit  exists  for  any  length  of  time,  the  pressure 
of  the  excess  hydrogen  will  speedily  ruin  it,  as  the  cell  will 


GAS,  OIL  AND  STEAM  ENGINES  209 

puff  up,  or.  even  burst  under  the  pressure.  If  the  rate  of  dis- 
charge be  kept  so  low  that  all  of  the  gas  will  be  absorbed  by 
the  manganese,  as  soon  as  generated,  the  cell  will  furnish  a 
steady  current  until  the  elements  of  the  cell  or  the  electrolyte 
are  exhausted. 

The  steady  current  limit,  or  non-polarizing  limit  is  about 
one-half  ampere  and  if  long  life  of  the  cell  is  expected,  the  cur- 
rent drain  should  be  less  than  this  amount.  A  good  spark 
coil  will  develop  a  satisfactory  spark  on  a  quarter  to  one-half 
ampere,  so  that  the  demand  of  a  good  coil  is  well  within  the 
safe  limits  of  battery  capacity.  The  voltage  of  the  average  dry 
cell  when  in  good  condition  is  1.5  volts  on  open  circuit.  When 
the  cell  is  old  or  exhausted,  the  voltage  falls  rapidly  when  any 
demand  for  current  is  made  on  the  cell,  and  the  voltage  also 
varies  with  the  rate  of  current  flow,  the  voltage  decreasing 
with  an  increase  of  .current. 

As  there  is  not  much  difference  in  voltage  between  a  new 
and  old  cell  when  on  open  circuit,  it  will  be  seen  that  the  am- 
meter giving  the  current  output  will  give  a  more  accurate  de- 
termination of  the  condition  of  the  battery.  The  voltage  is  in- 
dependent of  the  size  of  cell. 

The  battery  showing  the  greatest  amperage  is  not  neces- 
sarily the  best  for  general  use,  as  cells  having  an  unusually  high 
current  capacity  are  generally  short  lived.  The  strong  electro- 
lyte used  in  high  ampere  batteries  causes  them  to  burn  out  or 
deteriorate  rapidly  when  not  in  use. 

Under  ordinary  conditions,  a  correctly  proportioned  No.  6 
ignition  cell  should  show  a  current  of  from  fifteen  to  twenty 
amperes  on  short  circuit  when  the  cell  is  new,  although  higher 
results  may  be  obtained  safely  with  some  makes  of  cells. 

While  the  voltage  is  the  same  for  all  sizes  of  batteries,  and 
depends  on  the  material  used  in  the  construction,  the  amperes 
increase  with  the  size  of  the  cell,  and  the  area  of  the  electrodes. 

If  a  cell  does  not  show  more  than  ten  amperes  on  short  circuit, 
it  should  be  thrown  out  and  another  substituted  for  it,  as  the  cell 
is  liable  to  go  out  of  commission  at  any  minute  when  reaching 
this  point  of  exhaustion. 

A  small  battery  testing  voltmeter  or  ammeter  should  be  in 
the  kit  of  every  gas  engine  operator  using  a  battery  for  igni- 
tion, as  the  exact  condition  of  a  vital  part  of  the  power  plant 
can  be  determined  quickly  and  with  accuracy.  For  dry  bat- 
teries an  ammeter  is  preferable;  for  storage  batteries  a  volt- 
meter must  be  used. 


210  GAS,  OIL  AND  STEAM  ENGINES 

When  buying  dry  batteries  insist  on  having  new,  fresh  cells, 
as  any  battery  depreciates  in  value  with  age.  Never  take  a  cell 
without  testing  it,  as  it  is  the  practice  of  dealers  to  work  off 
their  old  stock  on  unsuspecting  customers.  Examine  the  bat- 
tery closely  for  the  makers'  dates,  and  if  the  battery  is  several 
months  old,  it  is  probable  that  the  electrolyte  is  dried  up  or 
that  the  electrodes  are  wasted  through  long  continued  local 
action.  As  heat  stimulates  chemical  action  in  the  cell,  they 
should  be  stored  in  a  cool  place  to  retard  the  wasting  action 
as  much  as  possible.  Under  all  conditions,  the  cell  should  be 
kept  dry,  since  the  moisture  that  is  deposited  on  the  cell  forms 
a  closed  circuit  for  the  current  which  soon  exhausts  the  battery. 
Cold  retards  chemical  action  in  the  cell  and  consequently  re- 
duces the  output  in  zero  weather  to  such  an  extent  that  start- 
ing is  frequently  impossible. 

Multiple  cylinder  engines  exhaust  a  battery  quicker  than 
those  with  a  single  cylinder,  as  there  are  more  current  impulses 
in  a  given  time  and  consequently  more  current  is  used.  A  bat- 
tery may  be  compared  with  a  bottle  that  holds  a  certain  quantity 
of  fluid.  If  the  water  is  allowed  to  drip  out  slowly  it  will  last 
for  a  long  time,  but  if  allowed  to  flow  in  a  continuous  stream 
will  soon  be  exhausted. 

With  badly  designed  or  poorly  adjusted  spark  coil,  the  de- 
mand on  the  batteries  is  greater  than  with  one  that  is  in  proper 
condition.  An  engine  that  runs  continuously  exhausts  a  battery 
faster  than  one  that  is  run  at  long  intervals.  Always  open  the 
battery  switch  when  the  engine  is  to  be  idle  for  any  length  of 
time,  as  the  engine  may  have  stopped  with  the  igniter  in  con- 
tact, allowing  the  battery  to  expend  its  energy  uselessly. 

Test  batteries  immediately  after  a  run,  as  the  batteries  will 
recover  after  standing  a  while,  and  will  show  a  fictitious  value. 

A  weak,  partially  exhausted  battery  will  cause  a  poor  spark 
that  will  result  in  misfiring  or  a  loss  of  power.  It  is  poor 
economy  to  attempt  running  an  engine  on  a  weak  battery.  An 
engine  may  run  on  a  weak  battery  for  a  short  time,  and  then 
gradually  decrease  in  speed  until  it  conies  to  a  full  stop.  Mis- 
firing is  generally  in  evidence  as  the  engine  dies  down.  In 
case  of  an  emergency,  weak  batteries  may  be  made  to  run  an 
engine  of  an  automobile  or  boat  to  its  destination,  by  stopping 
the  engine  frequently  and  allowing  the  batteries  to  recuperate 
during  the  idle  periods.  A  battery  that  is  temporarily  weak- 
ened by  hard  service  or  by  a  temporary  short  circuit  will  usually 
revive  or  partially  recover  its  strength  if  allowed  to  "rest"  for 


GAS,  OIL  AND  STEAM  ENGINES  211 

a  short  time  until  the  hydrogen  is  absorbed  by  the  depolarizing 
material.  The  life  of  a  dry  cell  can  be  extended  for  a  few 
hours  by  punching  a  hole  in  the  sealing  wax  on  the  top  of  the 
battery,  and  pouring  water,  or  a  solution  of  water  and  sal- 
ammoniac  into  the  cell.  This  will  reduce  the  internal  resistance 
and  increase  the  current.  The  batteries  will  run  under  these 
conditions  for  a  short  time  only,  and  new  cells  should  be  pro- 
cured at  the  earliest  possible  moment.  No  old  cell  can  be  made 
as  good  as  new  by  any  method.  Never  drop  the  cells  on  the 
floor  nor  subject  them  to  hard  usage  mechanically,  for  if  the 
active  material  is  loosened,  the  current  output  will  be  reduced. 
A  short  circuit  through  a  closed  switch  with  the  engine  stopped 
or  a  loose  dangling  wire  will  put  the  cells  beyond  repair. 

If  the  binding  screw  on  the  carbon  electrode  does  not  make 
good  contact  with  the  carbon,  tighten  it  to  decrease  the  re- 
sistance. Fasten  the  connecting  wires  firmly  under  the  bind- 
ing screws  and  keep  the  connections  clean. 

In  the  absence  of  an  ammeter,  a  rough  estimate  of  the  con- 
dition of  the  cell  may  be  made  by  fastening  a  short  wire  tightly 
in  the  zinc  binding  post,  and  touching  the  carbon  surface 
lightly  and  intermittently  with  the  free  end  of  the  wire.  When 
contact  is  made  with  the  free  end  of  the  wire,  a  small  puff  of 
smoke  will  arise  and  a  red  spark  will  be  seen  if  the  cell  is  in 
good  condition. 

Sometimes  the  contact  made  on  the  carbon  will  produce  only 
a  small  black  ring  on  the  surface  of  the  electrode.  This  indi- 
cates a  battery  that  is  nearly  exhausted,  and  one  which  is  good 
for  only  a  few  more  hours  of  service. 

When  a  number  of  cells  are  connected  together  in  such  a 
way  that  they  collectively  form  a  single  source  of  current,  the 
group  is  called  a  battery,  and  the  resulting  voltage  and  am- 
peres of  the  group  depends  on  the  way  in  which  the  cells  are 
interconnected. 

It  is  possible  to  connect  the  cells  of  a  battery  in  such  a  way 
that  total  voltage  of  the  group  or  battery  is  equal  to  the  sum  of 
the  voltages  of  the  individual  cells.  A  battery  connected  in 
this  manner  is  said  to  be  connected  in  series.  While  the  volt- 
age of  a  battery  is  increased,  by  series  connection,  the  number 
of  amperes  is  the  same  as  that  given  by  a  single  cell,  the  same 
current  flowing  through  the  set. 

(82)  Series  and  Multiple  Connections. 

Fig.  86  shows  the  cells  connected  in  series,  the  carbon  ter- 
minal of  one  cell  being  connected  to  the  zinc  terminal  of  the 


212  GAS,  OIL  AND  STEAM  ENGINES 

second.  The  carbon  of  the  second  cell  is  connected  to  the 
zinc  of  the  third,  and  so  on  throughout  the  series,  the  two 
remaining  terminals  of  the  battery  being  connected  with  the 
ignition  circuit.  The  number  of  watts  or  power  developed  by 
the  group  is  equal  to  the  sum  of  the  outputs  of  the  separate 
cells.  If  the  voltage  of  each  cell  shown  in  diagram  %is  1.5 
volts,  the  total  voltage  of  the  group  of  five  cells  will  be 
1.5X5  =  7.5  volts,  and  if  the  current  of  a  single  cell  is  15 
amperes,  the  current  output  of  the  group  will  be  15  amperes, 
or  the  same  as  that  of  a  single  cell.  Almost  all  ignition  appa- 
ratus now  on  the  market  requires  six  volts  for  its  operation, 
so  with  cells  having  a  voltage  of  1.5  volts  such  apparatus  would 
call  for  four  cells  in  series,  as  6  -f-  1.5  =  4. 

Owing  to  the  increase  of  internal  resistance  caused  by  series 
connections  it  is  usual  to  add  one  more  cell  than  is  theoretically 
required,  making  a  group  of  five  cells  to  supply  the  six  volts 


Fig.    86.     Five    Cells   in    Series. 

required.  A  large  number  of  cells  will  give  a  hotter  spark  than 
a  smaller,  but  the  excessive  current  causes  the  contact  points^ 
of  the  igniter  or  vibrator  to  burn  off  rapidly  and  also  hastens 
the  destruction  of  the  cells  themselves. 

Batteries  connected  in  such  a  way  that  the  total  amperes 
of  the  group  is  increased  without  increased  voltage  are  said 
to  be  connected  in  multiple  or  parallel.  When  batteries  are 
connected  in  multiple,  the  total  current  in  amperes  is  equal 
to  the  sum  of  the  amperes  delivered  by  the  separate  cells; 
and,  while  the  current  in  amperes  is  increased  by  multiple 
connection,  the  voltage  of  the  group  remains  equal  to  that 
of  a  single  cell. 

If  each  cell  connected  in  multiple  has  an  electromotive  force 
of  1.5  volts,  and  can  deliver  15  amperes,  the  total  current  de- 
livered by  this  system  of  connection  will  be  15  X  5  =  75  amperes 
with  five  cells,  and  the  electromotive  force  will  be  1.5  volts  as 
in  the  case  of  the  single  cell.  By  connecting  batteries  in  multiple, 
the  resistance  is  reduced,  allowing  a  maximum  flow  of  current. 
The  demand  on  the  individual  cells  is  reduced  by  multiple 


GAS,  OIL  AND  STEAM  ENGINES  213 

connection,  as  each  cell  only  furnishes  a  small  part  of  the 
total  current.  The  greater  the  number  of  cells,  the  less  will 
be  the  current  required  per  cell,  with  a  given  total  current. 
As  the  life  of  a  battery  depends  entirely  upon  the  rate  at  which 
it  is  discharged,  it  is  necessary,  for  economical  reasons,  to  keep 
the  current  per  cell  as  small  as  possible,  therefore  the  multiple 
system  would  prove  of  value  as  it  reduces  the  load  to  the  small- 
est possible  limit.  Enough  cells  should  be  placed  in  multiple 
to  reduce  the  current  to  less  than  a  quarter  of  an  ampere  per 
cell.  The  cells  shown  will  not  have  sufficient  voltage  to  oper- 
ate ordinary  ignition  apparatus  requiring  a  potential  of  six 
volts,  hence  the  multiple  system  must  be  modified  in  order  to 
have  an  increased  voltage,  and  at  the  same  time  secure  the 
advantages  of  multiple  connections. 

(83)  Multiple-Series  Connections. 

A  compromise  is  affected  by  the  multiple  series  system  of  con- 
nections in  which  are  combined  the  advantages  of  both  the 
series  and  multiple  systems  of  connection. 

This  arrangement  allows  sufficient  voltage  to  operate  6  volt 
apparatus  and  at  the  same  time  reduces  the  rate  of  discharge 
on  the  individual  cells.  The  series-multiple  battery  shown  in 
the  diagram  88  consists  of  four  groups  of  batteries  connected  in 
multiple,  each  group  of  which  consists  of  five  cells  that  are 
connected  in  series.  The  current  and  voltage  in  the  various 
branches  is  shown  in  the  diagram.  The  series-multiple  system 
is  adapted  for  use  with  multiple  cylinder  engines,  as  engines 
with  more  than  one  cylinder  cause  a  severe  drain  on  the  igni- 
tion system.  Arranging  the  series  groups  in  parrallel  increases 
the  life  and  efficiency  of  the  cells.  If  an  efficient  coil  is  used, 
the  drain  of  a  single  cylinder  is  not  too  great  to  be  met  with 
a  single  set  of  series  cells.  If  possible  the  set  should  be  pro- 
vided with  a  duplicate,  so  that  the  load  could  be  transferred 
from  -one  set  to  the  other  at  proper  intervals  by  means  of  a 
double  throw  switch. 

With  a  single  set  of  batteries  in  series  the  working  life  of 
the  cells  will  be  approximately  twenty  hours  under  ordinary 
conditions.  With  four  groups  of  four  cells  in  series,  the  life 
of  the  cell  will  be  approximately  160  hours,  or  eight  times  the 
life  of  the  single  set  under  similar  conditions. 

While  the  cost  of  the  cells  will  be  only  four  times  that  of 
the  single  set,  it  will  be  seen  that  the  cost  of  battery  upkeep 
is  halved  by  reducing  the  demand  on  the  cells. 


214  GAS,  OIL  AND  STEAM  ENGINES 

Sometimes  duplicate  sets  of  series  multiple  connected  bat- 
teries are  used  for  heavy  duty  engines,  the  engine  running  on 
one  set  for  a  while  and  then  on  the  other,  allowing  the  first  set 
to  thoroughly  recuperate  before  it  is  again  thrown  in  service, 
by  means  of  the  double  throw  switch. 

When  batteries  are  multiple  or  series-multiple  connected  they 
should  be  of  the  same  size  and  make. and  of  the  same  voltage. 
If  the  cells  are  of  different  voltages  useless  local  currents  will 
circulate  among  the  cross-connections,  shortening  the  life  of 
the  battery  and  reducing  the  output. 


Fig.   88.     Cells   in   Multiple   Series. 


In  connecting  a  dry  cell  use  a  good  grade  of  rubber  insulated 
wire,  preferably  wire  with  a  stranded  conductor,  as  it  is  less 
liable  to  break  or  loosen  at  the  binding  screw  of  the  battery. 
Carefully  remove  the  insulation  from  the  end  of  fhe  wire  that 
is  to  be  fastened  under  the  binding  screw  of  the  battery. 
Scrape  it  until  it  is  bright  and  perfectly  free  from  dirt  before 
fastening  it  in  the  battery  terminal.  Never  allow  a  dirty  or 
corroded  connection  or  a  loose  wire  to  exist.  An  open  battery 
circuit  or  loose  connection  will  stop  engine  suddenly,  or  will 
prevent  starting. 

The  battery  connections  should  be  screwed  down  tight  with 
the  pliers,  care  being  taken  that  the  screws  are  not  broken  by 


GAS,  OIL  AND  STEAM  ENGINES  215 

the  tightening  process.  See  that  frayed  ends  of  the  wire  do 
not  project  beyond  the  binding  screw  to  which  they  are  con- 
nected and  make  contact  with  other  cells  or  metal  objects.  Be 
sure  that  no  insulation  gets  between  the  contact  braces  of  the 
binding  screw. 

(84)  Operation  of  Dry  Cells. 

The  following  hints  should  be  observed  to  obtain  the  best 
results  with  dry  cells. 

(1)  Never  remove  the  paper  jackets  from  the  cells. 

(2)  Never  lay  tools  or  other  metallic  objects  on  top  of  the 
cells  for  this  will  cause  a  "short"  that  will  quickly  exhaust  them. 

(3)  Do   not   connect   old   and   new   cells   together,   especially 
with  the  multiple-series  system  of  connections,  for  the  old  cells 
will  limit  the  output  of  the  new,  or  else  will  cause  cross-cur- 
rents that  will  exhaust  all  of  them. 

(4)  When   trouble    developes    in    the   battery,    test    each    cell 
separately  and   remove  the  faulty  cells.     Do  not  reject  all  of 
the  battery  because  of  one  or  two  dead  cells. 

(5)  Place  the  cells  in  a  wooden  box  that  will  protect  them 
from  dirt  or  moisture,  and  if  possible  divide  the  box  off  into 
pigeon  holes  with  a  cell  in  each  hole.     For  the  best  protection 
against  moisture,  the  box  should  be  boiled  in  paraffine. 

(6)  Provide  a  battery  switch  on  the  box  that  will  cut  both 
leads   from   the   cells   completely   out   of  circuit  when   the   en- 
gine  is   stopped. 

(7)  Never  place  a  dry  cell  in  a  box  that  has  contained  stor- 
age cells  unless  the  box  has  been  thoroughly  washed  out,  for 
the  residual  acid  of  the  battery  will  destroy  the  zinc  elements. 

(8)  Make  all  connections  firmly  with  well  insulated  wire  and 
take  care  that  the  wire  does  not  make  contact  with  any  part 
of  the  battery  except  that  to  which  it  is  connected. 

(9)  Keep  the  battery  dry. 

(85)  Storage  Batteries. 

The  purpose  of  the  storage  battery  is  to  store  or  accumulate 
the  current  generated  by  a  dynamo  until  so  that  the  current 
will  be  available  when  the  dynamo  is  not  running.  A  storage 
cell  does  not  "store"  current  in  the  same  way  that  water  is  held 
in  a  tank,  but  returns  the  energy  expended  on  it  through  the 
chemical  changes  caused  in  the  cell  by  the  current. 

When  the  charging  current  passes  through  the  storage  bat- 
tery chemical  changes  are  produced  in  the  electrodes  and 


216  GAS,  OIL  AND  STEAM  ENGINES 

electrolyte,  and  the  energy  expended  on  the  cell  is  in  the  form 
of  latent  chemical  energy,  in  which  state  it  remains  until  the 
electrodes  are  connected  with  one  another  by  a  wire  or  some 
other  conducting  medium.  When  the  electrodes  are  connected 
through  an  external  circuit,  the  electrolyte  acts  on  the  elec- 
trodes causing  them  to  assume  their  original  composition.  As 
they  pass  into  their  previous  chemical  condition  the  latent  chem- 
ical energy  is  converted  into  electrical  energy.  The  current 
thus  produced  may  be  used  in  the  same  way  as  in  a  primary 
cell. 

When  discharging,  the  action  of  a  storage  battery  is  similar 
to  that  of  a  primary  battery,  the  current  being  produced  by  the 
action  of  a  fluid  on  two  dissimilar  electrodes.  Instead  of  sup- 
plying new  elements  when  the  battery  is  discharged,  as  in  the 
case  of  the  primary  cell,  the  elements  are  brought  back  to  their 
original  state  by  passing  a  current  through  the  cell  in  the  oppo- 
site direction  to  that  of  the  discharge. 

There  are  several  combinations  of  materials  which  may  be 
used  in  the  making  of  storage  battery  electrodes  and  electro- 
lytes, but  with  the  exception  of  the  lead  sulphuric  battery  and 
the  new  Edison  battery  none  have  proven  a  commercial  suc- 
cess. 

The  most  common  type  of  storage  or  secondary  cell  is  the 
lead-sulphuric  type  in  which  the  electrolyte  is  dilute  sulphuric 
acid  and  the  electrodes  are  lead  plates,  covered  with  a  chem- 
ical composition  known  as  the  active  material.  These  plates 
usually  consist  of  a  lead  grid',  or  lattice  frame  -in  the  pockets 
of  which  is"  pasted  the  active  material.  The  pockets  or  lattice 
bars  of  the  plates  are  for  the  purpose  of  supporting  the  active 
material  which  is  of  a  weak  and  spongy  nature.  The  active 
material  on  the  positive  plate  is  usually  litharge,  while  that 
on  the  negative  plate  is  red  lead. 

After  charging,  the  active  material  on  the  positive  plate  is 
changed  to  lead  peroxide  by  the  action  of  the  current,  and  the 
active  material  on  the  negative  plafe  is  changed  into  spongy 
metallic  peroxide.  The  composition  of  the  active  material  on 
the  plates  determines  the  direction  of  flow  of  the  discharge,  or 
secondary  current.  The  current  flows  from  the  positive  plate 
to  the  negative  through  the  external  circuit. 

When  fully  charged,  and  in  good  condition,  the  positive  and 
negative  plates  may  be  readily  distinguished  by  their  colors, 
the  positive  plate  being  a  dark  brown  or  chocolate  color,  and 
the  negative  a  slate  or  grey  color. 


GAS,  OIL  AND  STEAM  ENGINES  217 

The  positive  active  material  is  hard,  while  the  negative  may 
be  easily  cut  into  by  the  finger  nail.  The  density  of  the  ma- 
terial changes  slightly  with  the  charge,  as  the  material  ex- 
pands during  the  discharge. 

The  problem  of  holding  the  active  material  securely  to  the 
plates  during  expansion  and  contraction  has  been  a  hard  one 
to  solve,  each  manufacturer  having  some  favorite  form  of  grid 
or  material  plug  to  which  he  pins  his  faith.  While  great  im- 
provements have  been  made  in  this  direction,  it  is  certain  that 
we  have  not  yet  reached  perfection.  Loose  active  material  will 
cause  short  circuits  and  will  reduce  the  output  of  the  cell;  loose 
active  material  frequently  ruins  a  cell. 

The  current  capacity  of  a  storage  battery  depends  on  the 
area  of  the  plates  or  electrodes,  and  in  order  to  increase  the 
capacity  of  a  battery,  and  consequently  the  area,  it  is  usual  to 
use  a  number  of  plates  connected  in  parallel.  A  number  of 
small  plates  of  a  given  area  are  to  be  preferred  to  two  large 
plates  of  the  same  area,  as  the  battery  will  be  of  a  more  con- 
venient size. 

Customarily  there  is  one  more  negative  plate  than  positive, 
so  that  the  extreme  end  plates  in  a  cell  are  negative,  as  the 
positive  and  negative  plates  alternate  with  each  other  when  as- 
sembled. 

An  ignition  battery  usually  consists  of  two  negative  plates 
and  one  positive.  Cells  used  for  power  purposes  have  as  high 
as  sixty  plates. 

A  single  cell  of  storage  battery  should  show  about  two  volts 
when  fairly  well  charged.  It  more  than  two  volts  are  desired 
more  cells  should  be  connected  in  series.  The  total  voltage  will 
be  equal  to  the  number  of  cells,  in  series,  multiplied  by  the 
voltage  per  cell.  The  voltage  per  cell  should  never  be  allowed 
to  drop  below  1.7  volts,  as  the  cell  is  likely  to  be  destroyed 
when  operated  with  a  low  voltage.  Recharge  as  soon  as  the 
voltage  drops  to  1.8  volts. 

The  ordinary  six  volt  ignition  battery  consists  of  three  separ- 
ate cells  connected  in  series,  which  are  encased  in  one  protecting 
box. 

The  plates  are  prevented  from  touching  each  other  within  the 
cell  by  means  of  a  perforated  sheet  of  hard  rubber  that  is  in- 
serted in  the  space  between  the  plates.  The  perforations  allow 
the  liquid  to  circulate  between  the  plates. 

The  storage  battery  is  furnished  as  standard  equipment  with 
several  well  known  gas  engine  builders,  and  its  use  is  advocated 
by  nearly  all.  When  used  in  connection  with  a  low  tension 


218  GAS,  OIL  AND  STEAM  ENGINES 

direct  current  magneto  two  independent  sources  of  current  are 
at  hand,  either  of  which  will  ignite  the  engine  in  an  emergency. 

With  the  magneto-storage  battery  combination,  it  is  possible 
to  obtain  a  few  small  lights  at  any  time,  whether  the  engine  is 
running  or  not,  and  the  engine  is  always  ready  to  start  on  the 
first  "over"  with  the  storage  battery  and  a  good  mixture. 

If  a  magneto  is  not  used,  difficulty  is  sometimes  experienced 
in  obtaining  a  suitable  source  of  charging  current,  as  many 
localities  do  not  possess  direct  current  plants.  Batteries  may 
be  charged  from  the  direct  current  exciter  in  an  alternating 
current  station,  or  may  be  charged  by  an  alternating  current 
rectifier  such  as  is  used  by  automobile  garages. 

The  principal  objections  to  the  storage  cell  are:  inconvenience 
of  charging;  sulphating  of  cell  when  standing  without  a  charge; 
ease  with  which  the  cell  is  ruined  by  short  circuits;  the  damage 
caused  by  the  spilling  of  the  electrolyte;  and  the  fact  that  the 
cell  gives  no  warning  of  failing  or  discharged  condition. 

Since  the  composition  of  the  plates  depends  on  the  direction 
in  which  the  current  flows  through  the  cell,  it  is  obvious,  that 
an  alternating  current  which  periodically  changes  its  direction 
of  flow  will  first  charge  the  plates  and  then  discharge  them  al- 
ternately. The  result  of  an  attempt  at  charging  with  alternating 
current  would  be  that  the  plates  would  be  in  the  same  or  a 
worse  condition  in  a  short  space  of  time  than  they  were  at  the 
beginning.  In  charging  a  storage  cell  care  should  be  taken  to 
determine  the  character  of  the  current,  especially  when  the  cell 
is  to  be  charged  from  a  magneto.  When  under  charge,  the  cell 
is  connected  to  the  charging  circuit  in  such  a  way  that  the 
current  flows  backwards  through  the  cell  or  in  a  direction 
opposite  to  that  when  the  cell  is  discharging. 

(86)  Care  of  the  Storage  Cell. 

The  storage  battery  should  never  be  left  in  an  uncharged 
condition  with  the  acid  electrolyte  in  the  cell,  for  the  solution 
will  quickly  attack  the  uncharged  plates  and  combine  with  them 
to  form  lead  sulphate.  As  lead  sulphate  has  a  high  electrical 
resistance  and  is  insoluble  in  the  electrolyte  the  sulphate  coat- 
ing will  reduce  the  output  or  if  present  in  excess,  ruin  the  cell. 
The  sulphate  appears  as  a  white  coating  on  the  surface  of  the 
plates.  The  only  remedy  for  this  condition  at  the  hands  of  the 
average  engine  operator  is  a  prolonged  charge,  or  over  charge, 
at  a  slow  rate.  There  are  several  chemical  processes  but  they 
are  too  complicated  for  the  average  man. 


GAS,  OIL  AND  STEAM  ENGINES  219 

As  sediment  collects  on  the  bottom  of  the  battery  jars,  and 
is  liable  to  cause  a  short  circuit,  the  plates  should  be  held  about 
half  an  inch  from  the  bottom  of  the  jar.  Care  should  be  taken 
that  the  cells  of  the  stationary  type  of  battery  are  kept  dry  and 
clean.  Do  not  allow  dirt  to  drop  into  the  solution  as  it  is 
liable  to  destroy  the  cell. 

A  volt  meter  should  be  used  to  determine  the  condition  of 
the  battery,  and  should  be  used  frequently.  An  ammeter  should 
never  be  used  on  a  storage  battery,  as  it  is  of  very  low  resist- 
ance, and  would  probably  cause  a  rush  of  current  that  would 
destroy  both  the  battery  and  the  instrument. 

Never  short  circuit  a  storage  battery,  even  for  an  instant,  as 
excessive  current  will  cause  the  plates  to  buckle,  or  will  loosen 
the  active  material  on  the  plates. 

The  plates  are  immersed  in  the  electrolyte,  which  should  cover 
the  entire  plate  or  active  surface.  If  the  solution  does  not 
cover  the  plate,  the  capacity  of  the  cell  will  be  reduced.  Plates 
that  are  partially  covered  with  solution  deteriorate  rapidly  from 
"sulphating."  This  is  caused  by  the  air  and  acid  acting  on  the 
damp  inactive  portion  of  the  plate. 

Usually  the  electrolyte  consists  of  a  dilute  solution  of  sul- 
phuric acid  and  water,  but  in  some  ignition  cells  the  solution  is 
"solidified"  by  some  substance  to  about  the  consistency  of 
table  jelly.  The  object  of  this  thickened  solution  is  to  prevent 
the  solution  from  slopping  and  leaking  when  the  battery  is  being 
transported. 

The  solution  used  in  a  storage  battery  is  exceedingly  corrosive 
in  its  action,  and  if  spilled  on  metal  or  wood  will  destroy  it 
immediately.  Care  should  be  taken  in  handling  the  electrolyte. 

A  cell  should  never  be  discharged  below  1.7  volts  for  below 
this  point,  the  plates  are  likely  sulphate.  When  the  solution  is 
replaced  by  fresh,  or  water  is  added  for  the  purpose  of  restoring 
the  electrolyte  to  its  original  level,  use  only  distilled  water,  free 
from  metallic  salts  and  suspended  matter. 

Many  people  "test"  their  cells  by  snapping  a  wire  across  the 
terminals  to  "see  if  there  is  a  good  spark."  Nothing  could  be 
more  injurious  to  the  battery,  and  as  this  test  indicates  nothing, 
the  practice  should  be  discontinued.  Make  all  your  tests  either 
with  a  hydrometer  or  a  voltmeter,  the  latter  is  preferable  in  the 
average  case. 

The  electrolyte  is  a  solution  containing  approximately  10% 
of  chemically  pure  sulphuric  acid  and  90%  of  distilled  water. 
The  specific  gravity  of  the  fluid  should  be  from  1,210  to  1,212 


220  GAS,  OIL  AND  STEAM  ENGINES 

in  all  cases.  A  standard  battery  hydrometer  should  be  used  by 
all  storage  battery  users  to  ascertain  the  exact  density  of  the 
solution  as  the  specific  gravity  is  a  direct  index  to  the  condition 
of  the  cell.  A  gasoline  hydrometer  is  useless  for  a  storage 
battery. 

When  mixing  the  electrolyte  it  should  be  placed  in  a  glass 
or  porcelain  jar,  and  the  process  should  never  be  performed  in 
the  battery  jar  in  the  presence  of  the  plates.  The  solution  is 
very  active  chemically  and  should  not  be  brought  into  contact 
with  metallic  or  organic  substances  because  of  the  danger  of 
contaminating  the  fluid.  The  acid  should  always  be  poured  into 
the  water  in  a  thin  stream  while  the  mixture  is  being  stirred 
with  a  glass  or  porcelain  rod.  Pouring  the  water  into  the  acid 
is  likely  to  produce  an  explosion  and  should  therefore  be  care- 
fully avoided. 

As  the  acid  heats  the  water  during  the  mixing  the  hydrometer 
reading  should  not  be  taken  until  the  heat  caused  by  the  first 
addition  of  acid  has  been  reduced  to  that  of  the  room.  Taking 
a  reading  with  a  hot  solution  will  give  inaccurate  results,  un- 
less, of  course,  the  reading  is  reduced  to  normal  by  the  method 
described  in  a  previous  chapter.  When  the  reading  has  been 
taken  and  found  to  be  correct  and  the  solution  has  been  re- 
duced to  the  temperature  of  the  room,  the  electrolyte  may  be 
poured  into  the  cell  through  the  filler  openings  in  the  top  of 
the  cell.  Pour  into  each  cell  sufficient  fluid  to  cover  the  plates 
but  avoid  filling  the  cell  to  the  top,  or  flooding  it. 

At  the  end  of  the  charging  time  given  by  the  maker,  with- 
draw a  sample,  of  the  electrolyte  by  means  of  a  syringe  and 
test  the  specific  gravity.  This  should  not  be  over  1,290  fof  a 
fully  charged  cell,  and  if  the  solution  exceeds  this  amount,  pure 
water  should  be  added  until  the  proper  point  is  reached.  Al- 
ways correct  the  specific  gravity  in  this  way  every  time  the 
battery  is  charged  as  evaporation  and  internal  chemical  changes 
cause  the  density  to  change  from  time  to  time.  The  voltage  of 
a  good  storage  battery  will  be  about  2.1  volts  when  fully 
charged.  Overcharging  is  wasteful  and  finally  destroys  the 
cell,  the  effects  being  similar  to  those  caused  by  excessive  dis- 
charges, that  is,  buckled  plates  and  loosened  active  material. 
Overcharging  a  sulphated  battery  may  cure  the  trouble,  a 
little  overcharging  at  intervals  being  better  than  a  long  con- 
tinued overcharge. 

An  increase  in  the  specific  gravity  of  the  electrolyte  of  from 


GAS,  OIL  AND  STEAM  ENGINES  221 

30  to  50  degrees,  with  a  corresponding  rise  of  voltage,  shows 
that  the  cell  is  fully  charged. 

After  the  charging  is  completed  remove  all  of  the  solution 
spilled  on  the  battery,  preferably  by  washing,  and  wipe  bone 
dry.  If  the  solution  is  higher  in  the  air,  remove  the  excess 

with  the  syringe. 

i 

(87)  Make  and  Break  System  (Low  Tension). 

When  a  circuit  carrying  a  current  is  opened  or  broken  at 
any  place  in  its  length,  an  electric  spark  will  occur  at  the  point 
at  which  the  wires  or  contacts  are  separated.  This  is  due  to 
what  might  be  termed  the  "momentum"  of  the  current  which 
causes  it  to  persist  in  its  course  even  to  the  extent  of  jumping 
over  a  short  distance  of  the  highly  resistant  air  in  the  gap. 
The  size  and  heat  of  the  spark  may  be  increased  by  placing 
a  coil  of  copper  wire  in  series  with  the  circuit  that  has  an 
iron  core  in  the  center  of  the  turns.  This  coil  increases  the 
tendency  of  the  current  to  jump  the  gap,  or  in  other  words  in- 
creases the  momentum  of  the  circuit. 

Each  separation  of  the  terminals  of  the  circuit  causes  but  a 
single  spark,  so  that  in  order  to  obtain  another  the  terminals 
must  be  again  brought  into  contact  and  the  current  reestablished 
in  the  circuit  before  the  circuit  is  again  opened.  Thus  the  func- 
tion of  the  make  and  break  igniter  is  to  alternately  make  and 
break  the  circuit  in  the  presence  of  the  combustible  mixture. 
To  obtain  the  greatest  spark  and  most  certain  ignition,  the  con- 
tact points  should  be  opened  with  the  greatest  possible  speed, 
an  action  that  is  accomplished  in  the  actual  engine  by  springs 
and  triggers. 

A  typical  cylindrical  make  and  break  coil  consisting  of  an 
iron  wire  core  surrounded  by  a  coarse  copper  wire  core  is 
shown  by  Fig.  91.  At  one  end  of  the  coil  will  be  seen  the 
two  terminal  screws  by  which  it  is  connected  with  the  circuit. 
Another  make  and  break  coil  is  shown  by  Fig.  92,  which  has 
the  same  type  of  winding,  but  differs  in  having  the  core  wire 
coil  extended  beyond  the  winding  and  heads.  By  closely  exam- 
ining the  cut,  the  iron  wires  will  be  seen  in  the  projecting  core 
tube  at  the  left  end  of  the  coil.  A  flat  base  is  also  provided  for 
fastening  it  to  a  stationary  foundation. 

A  typical  make  and  break  igniter  is  shown  by  Fig.  93,  to- 
gether with  the  usual  circuit  consisting  of  a  primary  coil  and 
battery.  In  this  figure,  A  and  C  are  the  two  electrodes  pro- 
vided with  platinum  contact  points  N  and  O  respectively.  The 


222 


GAS,  OIL  AND  STEAM  ENGINES 


electrode  A  is  stationary  and  is  insulated  from  the  iron  casing 
K  by  the  insulating  washer  H,  and  the  insulating  bush- 
ing or  tube  I.  The  electrode  C  is  oscillated  intermittently  by 
the  engine  through  its  shaft  E,  and  the  trigger  G,  the  springs 
S  serving  to  snap  the  platinum  contact  O  away  from  N  at 
the  proper  moment.  This  electrode  (C)  is  in  electrical  con- 


Fig.    91.     Kingston    Cylindrical    Make    and    Break    Coil. 

nection  with  the  shell  K,  and  the  engine  frame  at  all  times, 
and  is  provided  with  a  brass  bushing  F  for  a  bearing  surface. 
The  outer  containing  casing  K  is  bolted  to  the  combustion 
chamber,  of  the  engine  by  the  bolts  LL,  so  that  the  electrodes 
A  and  C  project  into  the  combustion  chamber. 


Fig.   92.     Kingston   Make  and   Break   Coil.     Short  Type. 

Current  from  the  battery  R  passes  through  the  coil  winding 
P  to  the  coil  terminal  U  from  which  it  passes  from  V  to  the 
igniter  binding  post  J.  From  J  it  flows  along  the  rod  D  to 
the  stationary  electrode  A.  Since  the  rod  D  is  surrounded  by 
the  insulating  washers  and  tube  H,  T  and  I,  the  current  can- 
not escape  directly  to  the  casing  K.  With  the  two  platinum 
points  N  and  O  in  contact,  the  current  flows  through  C  to  the 
shell  K  from  which  point  it  flows  back  to  the  battery  R  through 
the  conducting  path  V,  completing  the  circuit.  The  greater 


GAS,  OIL  AND  STEAM  ENGINES 


223 


portion  of  the  path  V  consists  of  the  engine  frame.  When  the 
electrode  is  moved  in  the  direction  of  arrow  B,  the  current  is 
opened  and  a  spark  occurs  at  the  point  of  separation  M,  in  con- 
tact with  the  gas  in  the  combustion  chamber.  The  electrode 
C  being  connected  with  the  engine  frame  is  said  to  be 
"grounded."  If  the  stationary  electrode  A  were  not  insulated 
from  the  casting  K,  the  current  would  pass  directly  from  the 
terminal  J  back  to  the  battery  R  without  passing  through  the 
contact  points  at  all,  and  consequently  no  spark  would  be  pro- 
duced on  the  separation  of  the  points. 


Fig.   93.     Diagram   of   Igniter  and   Connections. 

A  push  rod  which  is  actuated  by  a  cam  on  the  engine,  en- 
gages with  the  trigger  G,  and  causes  the  spark  to  occur  when 
the  piston  is  on  the  end  of  the  compression  stroke.  In  nearly 
all  engines,  the  relation  between  the  time  of  the  spark  and  the 
piston  position  can  be  regulated  to  suit  the  requirements  for 
advance  and  retard.  This  adjustment  is  necessary  in  order 
that  the  spark  may  be  varied  to  meet  the  difference  between 
the  starting  and  running  requirements. 

While  the  ignition  should  be  considerably  advanced  while 
running,  it  is  necessary  to  retard  it  when  starting,  as  the  engine 
is  liable  to  "kick  back"  with  an  advanced  spark. 

This  advance  and  retard  device  should  be  accessible  while 
the  engine  is  running,  and  the  operator  should  be  able  to  control 


224  GAS,  OIL  AND  STEAM  ENGINES 

the  point  of  ignition  at  all  times.  Many  men  have  been  seriously 
injured  by  the  lack  of  this  device  or  by  neglecting  to  use  it. 

The  contact  points  make  contact  only  for  a  short  time  be- 
fore the  spark  is  required  in  order  to  reduce  the  amount  of  cur- 
rent to  the  minimum,  and  therefore  increase  the  life  of  the 
batteries. 

The  duration  of  the  "make"  or  contact  should  be  as  short 
as  possible.  Prolonged  contact  weakens  the  batteries  and  causes 
them  to  run  down  rapidly.  For  the  same  reason  the  electrodes 
should  remain  separated  until  the  make  is  actually  required. 

A  certain  period  of  contact  is  necessary,  however,  to  allow 
the  spark  coil  to  ''build  up,"  but  with  a  properly  designed  coil 
the  time  required  is  very  short. 

Some  engines  provide  a  device  that  cuts  out  the  ignition 
current  altogether  during  the  idle  strokes.  This  adds  materially 
to  the  life  of  the  batteries. 

The  igniter  should  be  located  near  the  inlet  valve,  as  the 
cold  incoming  gases  tend  to  keep  it  cool  and  clean,  besides 
insuring  the  presence  of  combustible  gas  around  the  igniter 
electrodes.  Improper  placing  of  the  igniter  will  greatly  reduce 
the  efficiency  of  the  engine.  Avoid  placing  the  igniter  in  a 
pocket,  or  in  the  path  of  the  exhaust  gases. 

The  make  and  break  ignition  system  has  many  good  features, 
but  cannot  successfully  be  applied  to,  engines  running  over  500 
revolutions  per  minute,  nor  can  it  be  applied  to  engines  of  less 
than  3  H.  P.  as  the  parts  would  be  too  small  and  delicate  to 
be  durable. 

The  make  and  break  igniter  produces  the  largest  and  "hottest" 
spark  of  any  type  of  ignition,  and  is  especially  derirable  for 
large  or  slow  running  engines.  Being  operated  at  a  low  volt- 
age, it  is  not  as  easily  affected  by  moisture,  poor  insulation,  or 
dirt  as  the  high  tension  or  jump  spark  system,  nor  is  it  liable 
to  give  the  operator  such  a  violent  "shock." 

Engines  governing  by  the  "hit  and  miss"  system  have  a 
device  that  cuts  out  the  current  during  the  "missed"  power 
strokes.  This  effects  a  considerable  saving  in  battery  current, 
especially  on  light  loads  when  the  engine  misses  a  great  num- 
ber of  strokes. 

While  possessing  many  points  of  merit,  the  make  and  break 
system  is  open  to  several  serious  objections: 

1.  Due  to  the  high  combustion  temperature  there  is  excessive 
wear  of  the  working  parts  in  the  cylinder,  this  wear  causes  a 
change  in  the  ignition  timing. 


GAS,  OIL  AND  STEAM  ENGINES  225 

2.  The  low  voltage  used  in  the  make  and  break  system  calls 
for  perfect  contact  of  the  electrodes  in  the  cylinder.    This  con- 
tact is  often  interfered  with  or  entirely  prevented  by  the  accu- 
mulation of  carbonized  oil  and  soot  deposited  on  the  surfaces. 

3.  The  wear  of  the  operating  spindle  or  shaft,  which  passes 
through  the  cylinder  wall  causes  leakage,  which  in  turn  causes 
a  loss  of  compression  in  the  cylinder. 

4.  The  wear  of  the  external  operating  mechanism  produces 
a  change  in  the  timing.     The  edge  of  the  fingers,  wiper  blades, 
etc.,  tend  to  cause  an  advance  in  the  ignition  as  a  general  rule, 
with  the  attendant  danger  of  broken  crank  shafts. 

5.  The  system  is  mechanically  complicated,  correct  operation 
calling  for  constant  care  as  to  adjustment. 

All  ignition  apparatus  wears  in  the  course  of  time  and  changes 
the  timing  of  the  engine.  The  electrodes  and  push-rods  wear 
and  require  readjustment.  Generally  the  tendency  of  worn 
parts  is  to  advance  the  ignition.  This  change  in  timing  occurs 
so  gradually  that  the  operator  does  not  notice  it  until  the  en- 
gine begins  to  pound,  or  until  the  efficiency  has  been  consider- 
ably reduced. 

When  the  engine  is  new  it  is  well  to  mark  the  ignition 
mechanism  in  such  a  way  that  the  relative  positions  of  the 
crank  and  igniter  will  be  shown  at  the  time  when  the  igniter 
trips.  It  will  then  be  possible  for  the  operator  to  refer  to  the 
marks  at  any  time  to  tell  whether  his  ignition  is  occurring  at 
the  proper  time.  Always  mark  the  half-time  gears  when  tak- 
ing the  engine  apart  for  the  difference  of  one  tooth  when 
reassembling  will  be  sufficient  to  throw  the  engine  out  of  time. 

The  usual  method  of  marking  the  gears,  is  to  center  punch, 
or  scratch  one  tooth  on  the  small  gear,  and  then  mark  the  two 
teeth  of  the  large  gear  that  lie  on  either  side  of  it.  With  these 
marks  it  is  possible  to  replace  the  gears  in  their  original  and 
proper  positions. 

The  igniter  should  trip,  causing  the  electrodes  to  separate 
just  before  the  end  of  the  compression  stroke  is  reached,  or 
just  before  the  crank  reaches  the  inner  dead  center.  The  dis- 
tance lacking  the  exact  dead  center  represents  the  instant  of 
time  between  the  time  of  ignition  and  the  actual  pressure  es- 
tablished by  the  combustion. 

As  most  engines  have  the  ignition  considerably  retarded  when 
starting,  the  igniter  will  trip  later  with  the  lever  in  the  "start" 
position  than  when  in  the  "running"  position.  Never  fail  to 
retard  spark  when  starting  nor  forget  to  advance  it  when 
engine  is  up  to  speed. 


226  GAS,  OIL  AND  STEAM  ENGINES 

The  actual  advance  given  to  an  engine  depends  on"  the  char- 
acter of  the  fuel  and  on  the  speed. 

An  engine  is  said  to  have  an  advance  of  10°,  if  the  crank 
lacks  10°  of  having  made  the  inner  dead  center  at  the  time 
of  ignition. 

The  most  economical  point  of  ignition  is  easily  determined 
when  the  engine  is  running  on  a  steady  load,  by  varying  the 
point  of  ignition  and  noting  the  position  assumed  by  the  gov- 
ernor. 

(88)  Operation  of  the  Make  and  Break  Igniter. 

To  keep  the  igniter  in  order,  and  to  obtain  the  best  results 
with  the  least  trouble,  the  following  hints  should  be  observed: 

(1)  Clean  the  igniter  frequently,  and  remove  all  deposits  of 
oil   and   carbon.      For   cleaning,    the   igniter   must   be    removed 
from  the  cylinder,  care  being  taken  to  avoid  injury  to  the  pack- 
ing or  gasket.     Graphite  dusted  on  the  gasket  will  prevent  it 
from  sticking  to  either  the  igniter  or  cylinder. 

(2)  If  the  contact  points  are  rough,  pitted,  or  covered  with 
a  carbon  deposit,  the  scale  should  be  removed,  and  the  points 
smoothed  down  with  a  fine  file,  taking  care  that  the  two  faces 
are  filed  parallel  with  one  another. 

(3)  Insulating  washers    and   tubes    should   be    removed   and 
washed  in  gasoline.     The  hole   through  which  the  igniter  rod 
passes  should  be  scraped  free  from  any  deposit  for  much  trou- 
ble can  be  caused  by  a  tight  working  shaft. 

(4)  Examine   the  hole   or  bushing  through  which   operating 
spindle  passes,  for  wear.    A  worn  spindle  or  bushing  may  cause 
a  serious  loss  of  compression;  replace  worn  bushing  at  once. 

See  that  the  insulation  of  the  stationary  electrode  is  not 
broken.  If  it  is  injured  in  the  slightest  degree,  replace  it  with 
new. 

(5)  Often   the   sparking  points   may  be   cleaned   temporarily 
without  removing  the  igniter  from  the  cylinder  by  pulling  upon 
the   outside   finger   or  trigger  until   the  points   come   together, 
and  then  pushing  in  towards  the  cylinder  several  times  on  the 
movable  electrode,  which  slides  them  one  on  the  other,  scrap- 
ing off  the  deposit.     This  method  is  only  a  make  shift. 

(6)  After  removing  igniter,  replace  all  wires,  screwing  them 
firmly  into  place.     The  ends   of  wires  and  connecting  screws 
should  be  perfectly  clean  when  the  conection  is  made;  to  insure 
perfect  contact,  the  surfaces  should  be  scraped  or  sand-papered 
until  bright  and   shining.     See   that  no  foreign  matter  of  any 


GAS,  OIL  AND  STEAM  ENGINES  227 

kind  gets  between  the  wires  and  the  metal  of  the  binding  screws. 
Wherever  possible  connections  should  be  soldered. 

(7)  A  small  coil  of  the  wire  should  be  made  at  the  point  of 
connection;  i.  e.,  the  wire  should  be  a  trifle  longer  than  neces- 
sary to  reach  the  binding  screw,  the  excess  wire  being  coiled 
up  on  a  pencil.    This  coil  allows  of  removing  igniter,  allows  for 
broken  wire  ends  and  reduces  the  tendency  to  loosen  the  con- 
nection. 

(8)  Ground  wires,  or  wires  connected  with  the  frame  of  the 
engine    should    receive    careful   attention.     They   are    generally 
fastened  under  some  screw  or  bolt  on  the  engine  which  may 
become  loose  or  fail  to  make  contact,  thus  opening  the  entire 
circuit  and  causing  the  engine  to  stop.     The  ground  wires  are 
generally  connected  in  inaccessible  places,  and  require  all  the 
more  attention  for  this  reason. 

(9)  For  the  primary  of  low  tension  wiring,  use  only  the  best 
grade  of  stranded  rubber  covered  wire.    A  special  wire  for  igni- 
tion purposes  is  on  the  market.     It  is  rather  expensive  but  is 
just  the  thing  for  the  service. 

Never  use  cotton  covered  or  waxed  wire.  This  covering  af- 
fords absolutely  no  protection  against  moisture  or  abrasion. 

(10)  As  the  voltage  of  a  primary  circuit,  or  circuit  for  make 
and  break  is  very  low,  and  the  current  comparatively  high,  it 
is  well  to  have  the  copper  as  large  as  possible.     It  should  never 
be  less  than  number  14  gauge.     Don't  use  solid  wire  if  you  can 
obtain   stranded  conductor.      (Stranded  wire   is   made  up   of  a 
number  of  fine  wires  which  are  twisted  into  a  cable  or  rope  of 
the  desired  size.) 

(11)  Oil  destroys  rubber  insulation  and  should  be  kept  off  the 
wiring.     Try  to  locate  the  conductors  so  that  they  will  be  out 
of  range  of  oil  thrown  by  the  moving  parts. 

(89)  Jump  Spark  System  (High  Tension  System). 

Due  to  its  simplicity  and  the  light  weight  of  its  moving  parts, 
the  high  tension  ignition  system  is  applied  to  practically  all 
small,  high  speed  engines  running  500  R.P.M.  or  over.  The 
high  tension  system  is  also  desirable  from  the  fact  that  it  has 
no  moving  parts  in  the  cylinder  of  the  engine. 

The  principal  objection  to  the  high  tension  system  is  the 
ease  with  which  the  high  voltage  current  leaks  or  short  circuits, 
moisture  being  fatal  to  the  operation  of  a  jump  spark  engine. 

Instead  of  producing  the  spark  by  breaking  the  circuit  of  a 
low  tension  current,  the  spark  is  produced  by  increasing  the  volt- 


228  GAS,  OIL  AND  STEAM  ENGINES 

age  to  such  a  point  that  the  current  will  jump  directly  across 
a  fixed  gap.  To  cause  the  current  to  jump  through  the  air 
requires  an  extremely  high  voltage,  and  as  the  battery  current 
is  very  low  it  is  necessary  to  introduce  a  device  known  as  a 
"transformer"  to  stop  the  current  up  to  the  required  tension. 
In  addition  to  the  voltage  required  at  atmospheric  pressure 
(about  50,000  volt  per  inch  of  spark)  we  must  also  furnish  suffi- 
cient pressure  to  overcome  the  increased  resistance  due  to  the 
compression  in  the  cylinder. 

Unlike  the  spark  coil  used  on  the  low  tension  make  and 
break  system,  the  induction  coil  or  transformer  coil  has  two 
separate  and  distinct  coils,  that  are  thoroughly  insulated  from 
each  other.  One  coil  has  a  few  turns  of  heavy  copper  wire 
which  is  called  the  primary.  The  other  consists  of  many  thou- 
sands of  turns  of  very  fine  copper  wire,  and  is  called  the  sec- 
ondary. Both  coils  are  wound  around  a  bundle  of  soft  iron 
wire  called  the  core,  from  which  they  are  carefully  insulated. 
When  a  battery  or  magneto  current  flows  through  the  primary 
coil,  the  core  is  magnetized,  and  throws  its  magnetic  influence 
through  the  turns  of  the  secondary  coil. 

In  Fig.  94  the  primary  coil  and  the  low  tension  battery  and 
magneto  circuit  are  represented  by  heavy  lines.  The  second- 
ary coil,  and  high  tension  circuit  are  represented  by  light  lines. 

In  order  to  obtain  a  continuous  discharge  of  sparks  it  is 
necessary  to  make  and  break  the  current  in  the  primary  coil 
very  rapidly.  This  is  done  by  means  of  the  interrupter  or 
vibrator,  which  is  indicated  in  the  diagram  by  V.  The  inter- 
rupter consists  ordinarily  of  a  spring  A  on  which  is  fastened  a 
soft  iron  disc  D  and  a  platinum  contact  point  B.  When  the 
core  is  magnetized  it  attracts  the  iron  disc  D  which  is  pulled 
toward  the  core,  bending  the  spring  A  and  breaking  the  con- 
tact between  the  platinum  point  B  and  C.  When  the  contact 
points  are  separated,  and  the  current  broken,  the  core  loses  its 
magnetism,  and  the  spring  assumes  its  normal  position,  which 
brings  the  platinum  points  B  and  C  into  contact  once  more,  and 
reestablishes  the  current  through  the  primary.  The  core  is 
again  magnetized  and  the  primary  current  is  again  broken,  and 
so  on.  This  make  and  break  of  the  current  is  thus  accom- 
plished automatically,  the  current  being  broken  many  thousands 
of  times  per  minute,  the  vibrator  moving  so  fast  as  to  cause 
a  continuous  hum. 

As  soon  as  the  current  starts  flowing,  the  magnetic  force 
spreads  out  through  the  secondary  coil  and  threads  through  the 


GAS,  OIL  AND  STEAM  ENGINES 


229 


turns  of  which  it  is  composed.     The  instant  that  the  current 
ceases,  the  magnetic  force  decreases  and  the  turns  are  again 
threaded  by  the  magnetic  field  on  its  return  to  the  core. 
Thus   two   magnetic   waves   are   sent   through   the   secondary 


coil,  one  when  the  circuit  is  "made,"  and  one  when  the  circu 
is  "broken." 

When  a  magnetic  wave  threads  or  spreads  through  the  tun 
of  a  coil  of  wire,  a  current  of  electricity  is  generated  in  the  co 
the  quantity  and  pressure  or  voltage  of  which  is  proportion 


230  GAS,  OIL  AND  STEAM  ENGINES 

to  the  intensity  of  the  magnetism,  and  to  the  number  of  turns 
of  wire  in  the  secondary  coil. 

Thus  it  will  be  seen  that  at  every  make  and  break  of  the  low 
tension  current  in  the  primary  coil,  a  current  is  generated  in 
the  secondary.  As  the  voltage  generated  in  the  secondary  is 
roughly  proportional  to  the  number  of  turns  in  the  secondary, 
and  as  there  are  many  thousands  of  turns,  it  is  evident  that 
the  voltage  in  the  secondary  will  be  very  high.  Thus  by  the 
use  of  the  induction  coil,  the  low  tension  battery  current  is 
transformed  into  a  high  tension  current  of  sufficient  voltage  to 
break  down  the  high  resistance  of  the  spark  gap. 

The  condenser  is  shown  at  L  which  has  one  wire  leading  to 
the  vibrator  spring  A,  and  one  wire  to  the  contact  screw  M. 
The  function  of  the  condenser  is  to  absorb  the  spark  produced 
at  the  vibrator  points  so  that  the  break  is  made  quickly,  produc- 
ing a  maximum  spark.  The  intensity  of  the  spark  depends  upon 
the  quickness  with  which  the  primary  current  is  broken,  and 
if  it  were  not  for  the  condenser  the  length  and  intensity  of  the 
spark  would  be  greatly  reduced.  This  device  consists  of  alter- 
nate layers  of  paper  and  fin  foil,  every  other  leaf  of  foil  being 
alternately  connected  to  the  vibrator  spring  and  to  the  con- 
tact screw. 

A  method  of  using  two  independent  sets  of  battery  is  shown 
in  the  diagram,  so  that  either  set  may  be  thrown  into  circuit 
by  means  of  the  double  throw  switch  O.  When  handle  J  is 
in  contact  with  E,  the  current  of  battery  set  H  flows  through 
the  coil  as  shown  by  the  arrows.  When  J  is  in  contact  with  F, 
the  battery  C  is  thrown  into  circuit.  The  spark  gap  is  shown 
by  X,  which  represents  the  spark  plug  in  the  cylinder. 

In  practice,  the  portion  of  the  circuit  shown  by  I-U  is  gen- 
erally formed  by  the  frame  of  the  engine,  or  is  grounded.  The 
terminal  P  of  the  high  tension  circuit  is  always  grounded 
through  the  threaded  shell  of  the  spark  plug,  the  grounded 
circuit  being  shown  by  the  dotted  lines.  Grounding  saves  wire 
and  many  connections,  for  with  P  and  U  connected  to  ground 
it  follows  that  one  binding  post  will  serve  the  place  of  one  high 
tension  and  one  primary  post,  making  .three  coil  connections 
instead  of  four. 

In  order  that  the  spark  will  occur  in  the  cylinder  of  the 
engine  at  the  proper  time,  a  switch  must  be  placed  in  the  pri- 
mary circuit  of  the  soil,  that  will  open  and  close  the  circuit 
at  proper  intervals.  Such  a  switch  is  called  a  timer,  and  is 
always  driven  by  the  engine.  The  timer  is  connected  to  the 


GAS,  OIL  AND  STEAM  ENGINES  231 

engine  shaft  in  such  a  way  that  contact  is  made  at,  or  slightly 
before,  the  time  at  which  the  explosion  is  required,  and  as 
soon  as  possible  after  spark  occurs  the  current  is  cut  off. 

For  multiple  cylinder  engines  it  is  usual  to  provide  one  coil 
for  each  cylinder,  the  primaries  of  which  are  controlled  by  a 
single  timer  and  battery.  A  high  tension  wire  from  each  coil 
runs  to  the  corresponding  cylinder.  Instead  of  having  a  num- 
ber of  coils  with  a  battery  system,  there  are  two  or  three  makes 
that  operate  with  one  coil  in  combination  with  a  special  de- 
vice known  as  a  distributor  which  controls  the  high  tension 
current.  The  high  tension  distributor  directs  the  current  to  the 
proper  cylinder  that  is  in  the  order  of  firing,  the  timing  being 
performed  by  a  timer  similar  to  that  used  with  multiple  coils 
except  that  a  single  contact  sequent  is  supplied. 

(90)  Vibrator  Construction. 

Since  the  efficiency  of  the  high  tension  coil  depends  largely 
on  the  construction  and  efficiency  of  the  vibrator,  the  different 
coil  makers  have  developed  various  types  of  vibrators  that  differ 


Fig.    95.     Kingston    Vibrator. 

greatly  from  the  simple  device  shown  in  the  coil  diagram  in 
details. 

The  main  objects  in  view  in  the  construction  of  a  successful 
vibrator  are: 

1.  To  reduce  the  weight  of  the  moving  part  as  much  as  pos- 
sible in  order  to  increase  the  speed  of  vibration,  and  to  make 
the  trembler  instantly  responsive  to  the  timer. 


232  GAS,  OIL  AND  STEAM  ENGINES 

2.  To  cause  the  contact  points  to  separate  as  rapidly  as  pos- 
sible in  order  to  cause  the  maximum  spark. 

3.  To  have  the  contacts  as  hard  and  infusible  as  possible 
to  resist  wear  and  the  action  of  the  spark  between  the  contacts. 

4.  To  make  any  adjustments  that  may  be  required,  due  to 
wear,  as  simple  and  accessible  as  possible. 

The  types  of  vibrators  are  legion,  and  we  have  not  the  space 
to  go  into  the  details  of  all  the  prominent  makes,  but  will  illus- 
trate and  describe  two  well  known  types. 

The  Kingston  vibrator  made  by  the  Kokomo  Electric  Com- 
pany, is  a  good  example  of  a  modern  vibrator  and  is  shown  in 
detail  by  Fig.  95.  All  adjustments  between  the  contact  points 
are  made  by  means  of  the  contact  screw  A  which  carries  a 
platinum  point  at  its  inner  end.  The  retaining  spring  D  keeps 
the  contact  screw  from  being  jarred  out  of  place  by  the  engine 
vibration,  without  the  use  of  lock  nuts.  Turning  A  against  the 
vibrator,  the  tension  of  the  spring  B  is  increased,  raising  the 
creases  the  length  and  heat  of  the  spark,  and  also  increases 
screw  decreases  the  tension.  Increasing  the  tension  screw  in- 
the  current  consumption.  At  N  is  a  separate  thin  iron  plate 
which  is  acted  on  by  the  magnetized  core,  a  rivet  fastening  the 
plate  to  the  main  vibrator  spring  is  shown  at  the  end  of  the 
spring.  The  current  enters  through  the  lug  C,  and  from  this 
point  the  circuit  is  the  same  as  shown  in  the  coil  diagram. 

(91)  Operation  of  the  Jump  Spark  Coil. 

The  spark  produced  by  a  coil  in  good  condition  should  be 
blue-white  with  a  small  pinkish  flame  surrounding  it,  when  the 
gap  is  y$  of  an  mcn  or  less-  The  sparks  should  pass  in  a  con- 
tinuous stream  with  this  length  of  gap  without  irregular  stop- 
ping and  starting  of  the  vibrator.  Coils  giving  a  sputtering, 
weak  discharge  that  causes  sparks  to  fly  in  all  directions  are 
broken  down  and  should  be  remedied. 

The  secondary  windings  of  coils  are  often  punctured  or 
broken  down  by  operating  the  coil  with  the  high  tension  circuit 
open,  or  by  trying  to  cause  long  sparks  by  increasing  the  spark 
gap  over  ^  of  an  inch  in  the  open  air.  Coils  are  also  broken 
down  by  allowing  excessive  currents  to  flow  in  the  primary  coil. 
Never  cause  a  spark  to  jump  over  ^  of  an  inch. 

High  compression  in  the  cylinder  shortens  the  jumping  dis- 
tance of  a  high  tension  spark.  Coils  that  will  cause  a  stream 
of  sparks  to  flow  across  a  gap  of  ]/2  an  inch  in  the  open  air 
are  often  unable  to  cause  a  single  spark  to  jump  a  gap  of  3*2 


GAS,  OIL  AND  STEAM  ENGINES  233 

of  an  inch  under  a  compression  of  80  pounds  per  square  inch  in 
the  cylinder. 

Remember  that  a  hot  spark  causes  rapid  combustion,  and 
will  fire  a  greater  range  of  mixtures  and  "leaner"  charges,  than 
a  straggling,  thin,  weak  spark.  Spark  coils  that  give  poor 
results  with  a  long  spark  gap  under  high  compression  aTe  often 
benefited  by  the  shortening  of  the  spark  gap.  Shortening  the 
gap  will  increase  the  heat  of  the  spark,  and  will  insure  the 
passing  of  a  spark  each  time  that  the  timer  makes  contact.  A 
good  coil  should  have  no  difficulty  in  igniting  a  piece  of  paper 
inserted  between  the  wires  forming  the  spark  gap  in  the  open 
air. 


Fig.   96.     Kingston  Dash  Coil. 

The  adjusting  screw  affords  a  means  of  increasing  or  de- 
creasing the  tension  of  the  vibrator  spring,  and  the  amount  of 
battery  or  magneto  current  flowing  through  the  primary  coil. 
Increasing  the  tension  of  the  spring  requires  stronger  magnetiza- 
tion of  the  core  to  break  the  circuit  of  the  contact  points.  This 
in  turn  calls  for  more  current  from  the  battery;  hence  in  order 
to  lessen  the  demand  for  current  on  the  battery,  the  tension 
should  be  as  little  as  possible  to  obtain  the  necessary  spark. 
An  increased  tension  produces  more  spark  as  the  magnetization 
of  the  core  is  increased,  but  for  the  sake  of  your  batteries  de- 
crease the  tension  as  much  as  possible  with  a  satisfactory  spark. 

Almost  all  operators  have  a  tendency  to  run  with  too  stiff 
a  vibrator,  and  hence  use  too  much  current.  An  efficient  coil 
should  develop  a  satisfactory  spark  with  l/±  to  ^  of  an  ampere 
of  current  in  the  primary  coil.  I  have  often  found  coils  that 
would  work  well  with  ]/2  ampere,  that  were  screwed  up  so  tight 
that  the  coils  were  consuming  4  to  5  amperes  or  8  to  10  times 
as  much  as  they  should. 


234  GAS,  OIL  AND  STEAM  ENGINES 

A  battery  ammeter  used  for  testing  the  current  consumed  by 
coil  will  save  its  cost  many  times  over  in  batteries  and  burnt 
points  if  used  at  frequent  intervals  in  the  primary  circuit. 

An  automobile  or  marine  engine  should  be  tested  for  vibrator 
adjustment  in  the  following  way: 

Adjust  vibrator  so  that  spring  is  rather  stiff.  Start  engine 
and  get  it  thoroughly  warmed  up  and  running  at  full  speed,  then 
slowly  and  gradually  decrease  the  tension  of  the  spring  until 
misfiring  starts  in;  then  slowly  increase  tension  until  misfiring 
stops.  Increase  the  tension  no  farther;  this  is  the  correct  ad- 
justment. 

Poor  vibrator  adjustment  is  the  cause  of  much  trouble  and 
expense  as  it  uses  up  the  batteries  and  wastes  fuel.  The  prin- 
ciples of  correct  adjustment  are  simple,  the  adjustment  easily 
made,  and  there  is  no  possible  excuse  for  the  high  current  con- 
sumption and  rapid  battery  deterioration  met  in  every  day 
practice.  The  usual  practice  of  the  average  operator  is  to 
tighten  the  vibrator  until  the  spark  (observed  in  the  open  air) 
is  at  its  maximum.  This  is  commonly  known  as  "adjusting  the 
coil;"  shortly  after  you  hear  of  him  thi owing  out  his  batteries  as 
no  good.  After  once  getting  the  vibrator  in  proper  trim  the 
ear  will  give  much  information  as  to  the  adjustment. 

A  vibrator  adjusted  too  lightly  will  cause  "skipping"  or  mis- 
firing with  the  consequent  loss  of  power. 

Never  attempt  to  operate  a  coil  that  is  damp;  the  coil  will  be 
ruined  beyond  repair.  Above  all,  do  not  place  the  coil  in  a 
hot  oven  to  dry,  as  the  box  is  filled  with  wax,  and  if  this  is 
melted  it  will  run  out  and  reduce  the  insulation  of  the  coil.  Dry 
coil  gradually. 

If  the  batteries  are  new  or  too  strong  the  vibrator  may  be 
held  against  the  core  of  the  coil  so  that  the  vibrator  will  not 
buzz.  If  this  is  the  case  loosen  the  screw  until  it  works  at  the 
proper  speed.  -If  the  batteries  are  weak,  the  coil  may  not  be 
magnetized  sufficiently  to  draw  the  vibrator  and  break  the  cir- 
cuit. If  this  is  the  case  tighten  the  screw.  If  the  vibrator 
refuses  to  work  with  the  battery  and  wiring  in  good  condition, 
and  if  you  are  sure  that  the  current  reaches  the  coil,  look  for 
dirty  or  pitted  contacts  on  the  vibrator. 

Should  the  contact  points  be  dirty,  clean  them  thoroughly 
by  scraping  with  a  knife  or  sandpaper.  Water  on  the  points 
will  stop  the  vibrator,  as  will  oil  or  grease. 

If  contact  points  are  of  a  uniform  gray  color  on  their  con- 
tact surfaces,  and  are  smooth  and  flat  without  holes,  pits  or 


GAS,  OIL  AND  STEAM  ENGINES  235 

raised  points,  they  are  in  good  condition.  If  pits,  discolorations 
or  projections  are  noted,  the  contact  surfaces  should  be  brought 
to  a  square,  even  bearing  by  means  of  a  small,  fine  file.  Th^ 
point  should  not  come  into  contact  on  an  edge,  but  should 
bear  on  each  other  over  their  entire  surface.  Do  not  use  sand 
paper  to  remove  pitting,  as  it  is  almost  impossible  to  secure  an 
even,  flat  surface  by  this  means. 

It  is  best  to  remove  the  contact  screw  and  vibrator  blade  for 
examination  and  cleaning,  as  it  is  much  easier  to  file  the  points 
square  and  straight  when  removed  from  the  coil. 

Be  careful  not  to  bend  the  vibrator  spring  when  cleaning,  as 
the  adjustment  will  be  impaired.  When  replacing  con^ct  screw 
and  vibrator  blade  in  coil,  be  careful  that  they  are  in  exactly 
the  same  relative  position  as  they  were  before  removing.  Also 
be  sure  that  the  contacts  meet  and  bear  uniformly  on  their 
surfaces. 

(92)  Primary  Timer. 

The  duty  of  the  primary  timer  is  to  close  the  primary  circuit 
of  the  spp.rk  coil  at,  or  a  little  before  the  time  at  which  the 
explosive  of  the  charge  is  required.  The  exact  time  at  which 
the  timer  closes  the  circuit  depends  on  the  load,  the  speed,  and 
the  nature  of  the  fuel.  The  lapse  of  time  between  the  instant 
that  the  timer  closes  the  circuit  and  the  instant  at  which  the 
piston  reaches  the  end  of  the  compression  stroke  is  called  the 
"advance"  of  the  timer.  When  the  timer  closes  the  circuit  after 
the  piston  reaches  the  end  of  the  stroke,  the  timer  is  said  to  be 
"retarded."  The  timer  is  constructed  so  that  the  time  of  igni- 
tion or  the  advance  and  retard  can  be  varied  between  wide 
limits.  Advancing  the  spark  too  far  will  cause  hammering  and 
power  loss  as  the  piston  will  work  against  the  pressure  of  the 
explosion. 

Retarding  the  spark  will  cause  a  loss  of  power,  as  the  com- 
pression will  be  less  when  the  piston  starts  on  the  outward 
stroke;  and  also  for  the  reason  that  more  of  the  heat  will  be 
given  up  to  the  cylinder  walls  as  the  combustion  will  be  slower. 
The  pressure  in  the  cylinder  is  less  with  retarded  ignition. 
Greatly  retarded  ignition  often  causes  overheating  of  the  cyl- 
inder walls,  especially  with  air  cooled  engines,  and  also  over- 
heats and  destroys  the  seat  and  valve  stem  of  the  exhaust  valve. 
Do  not  expect  the  engine  to  develop  its  rated  horse-power  or 
run  efficiently  with  a  late,  or.  retarded  spark. 

When  the  engine  is  installed,  and  before  the  timer  wears  or 


236  GAS,  OIL  AND  STEAM  ENGINES 

has  a  chance  to  get  out  of  adjustment,  look  it  over  carefully 
and  see  whether  the  maker  has  left  any  marks  relating  to  the 
timing  of  the  spark.  If  there  are  no  marks,  it  is  well  to  deter- 
mine the  relation  between  the  position  of  the  piston  and  the 
timer,  as  the  efficiency  of  the  engine  depends  to  a  great  degree 
upon  the  firing  point. 

Timers  are  advanced  and  retarded  by  partially  rotating  the 
housing  either  in  one  direction  or  the  other.  When  the  timer 
is  mounted  directly  on  the  cam  shaft  with  the  cam  shaft  travel- 
in  a  direction  opposite  to  that  of  the  crank  shaft,  the  timer  will 
be  retarded  by  moving  it  in  the  same  direction  as  the  cam 
shaft  travels,  moving  it  against  cam  shaft  rotation  advances 
the  spark. 

Timers  for  two  stroke  cycle  engines  rotate  at  crank  shaft 
speed,  and  the  direction  of  advance  and  retard  varies  with  the 
methods  adopted  for  driving  the  timer. 

(93)  Timer  Construction. 

Fig.  97  shows  a  typical  timer  and  circuit  arranged  for  a  four 
cylinder  engine.  The  device  can  be  arranged  for  any  number 
of  cylinders,  however,  by  changing  the  number  of  sectors,  the 
sectors  being  equal  to  the  number  of  cylinders.  There  are 
timers  on  the  market  that  differ  from  the  one  shown  in  the 
diagram  but  the  principle  of  operation  is  the  same  with  all.  The 
shaft  E  is  usually  connected  to  the  cam  shaft  and  is  electrically 
grounded  to  the  engine  frame  at  L*  by  means  of  the  bearing  in 
which  the  shaft  rotates. 

The  lever  F  mounted  on  the  shaft  E  carries  the  pivoted  arm 
H  which  is  free  to  move  on  the  pivot  to  a  limited  extent  to 
allow  for  wear  on  the  walls  W-W-W-W.  At  one  extremity  of 
H  is  the  roller  I  which  rotates  on  the  pin  J,  as  the  roller  runs 
around  W-W-W-W.  At  the  other  extremity  of  H  is  fastened 
the  spring  S,  which  forces  I  into  contact  with  the  walls. 
A-B-C-D  are  metallic  contact  sectors  whose  connections  lead 
to  the  four  spark  coils. 

When  the  metal  roller  I  comes  into  contact  with  one  of  the 
sectors  as  at  B,  the  sector  is  grounded  to  the  engine  frame  by 
the  roller,  the  current  traveling  through  the  roller  and  its  pin, 
through  lever  H  and  its  pin,  through  the  lever  F  and  shaft  E  to 
ground  at  L,  the  course  of  the  current  being  indicated  by  the 
arrows. 

As  the  shaft  E  rotates  and  carries  wfth  it  roller  I,  the  roller 
makes  contact  with  the  sectors  in  order  B-C-D-A,  if  rotated  in 


GAS,  OIL  AND  STEAM  ENGINES 


237 


the  direction  shown  by  arrow,  which  rotation  grounds  the  pri- 
mary coils  of  the  spark  coils  R3-R4-R1-R2  in  succession;  the 
connection  from  the  timer  to  the  primary  being  to  the  primary 


Fig.   97.     Timer   Diagram. 

binding  posts  P3-P*-P1-P2.  A  high  tension  spark  occurs  at  each 
contact  of  the  roller  with  the  sectors,  as  the  contact  allows  cur- 
rent to  flow  through  the  primary  of  the  coils.  The  high  tension 


238  GAS,  OIL  AND  STEAM  ENGINES 

binding  posts  S1-S2-S3-S4  are  connected  with  the  spark  plugs 
or  spark  gaps  TJi-U'Z-lJs-U4  by  means  of  high  tension  cables. 
As  soon  as  the  timer  grounds  a  coil,  the  coil  produces  a  high 
tension  spark  in  its  corresponding  spark  plug. 

It  is  evident  from  the  foregoing  that  the  timer  not  only  deter- 
mines the  time  at  which  a  spark  will  take  place,  but  it  also 
determines  the  cylinder  in  which  the  spark  will  be  produced, 
providing  of  course  that  a  spark  coil  is  provided  for  each 
cylinder. 

The  contact  sectors  A-B-C-D  are  insulated  from  each  other 
by  the  insulating  walls  W-W-W-W,  the  inner  surface  of  which 
provides  a  path  on  which  the  contact  roller  I  revolves. 

The  contact  sectors  and  insulating  walls  are  encased  by  the 
protective  housing  Z,  to  which  they  are  rigidly  fastened. 

The  housing  Z  can  be  moved  back  and  forth  on  the  shaft  E 
for  advance  and  retard,  by  means  of  the  lever  K. 

The  current  flows  from  the  battery  terminal  V  (with  the  roller 
in  the  position  shown)  through  the  switch  M,  through  coil  R3, 
post  P3  to  sector  B,  from  which  it  passes  through  the  roller  I, 
levers  H  and  F  to  ground.  From  the  ground  on  the  engine 
frame  the  current  flows  back  to  its  source,  the  battery  O,  thus 
completing  the  circuit.  When  the  roller  makes  contact  with 
sector  C,  the  coil  R*  is  energized,  contact  with  D  energizes  R1, 
and  so  on.  No  two  coils  can  be  thrown  on  simultaneously  as 
only  one  coil  is  grounded  at  a  time.  The  high  tension  current 
flows  from  each  coil  to  its  plug  as  soon  as  the  current  passes 
through  the  primary  of  that  coil. 

In  some  timers,  the  current  is  taken  from  the  revolving  arm 
through  a  separate  connection  to  ground  instead  of  grounding 
the  shaft  through  the  bearings.  With  these  timers,  the  connec- 
tion is  not  affected  by  worn  bearings  or  an  oil  film  that  tends 
to  insulate  the  shaft  from  the  bearings. 

(94)  Operation  of  Timers. 

Timers  frequently  cause  misfiring  which  is  generally  due  to 
dirt  or  oil  getting  between  the  contacts,  or  to  the  wear  of  the 
insulating  walls  W-W-W-W,  or  to  the  wear  of  the  moving  parts. 

Dirt  or  gummy  oil  will  prevent  the  contact  coming  together 
and  completing  the  circuit,  or  will  clog  up  the  rollers  or  levers 
so  that  they  cannot  perform  their  functions  properly.  This 
will  of  course  interfere  with  production  of  the  spark. 

The  contacts  and 'moving  parts  of  the  timer  should  be  kept  as 
clean  as  possible,  all  dirt  and  heavy  oil  being  removed  by  means 


GAS,  OIL  AND  STEAM  ENGINES  239 

of  gasoline  at  regular  periods.  Make  a  practice  of  cleaning  out 
the  timer  at  intervals  not  greater  than  one  month;  oftener  if 
possible. 

Parts  subject  to  wear,  such  as  the  roller  pin  J  and  the  bear- 
ings should  be  well  lubricated,  none  but  the  lightest  oil  being 
employed  for  this  purpose.  Heavy  grease  will  gum  the  con- 
tacts and  cause  trouble.  There  should  be  no  rough  places  or 
shoulders  on  the  contact  sectors  or  on  the  walls  W-W-W-W 
as  roughness  will  cause  the  roller  to  jump  over  the  high  places 
which  in  turn  result  in  misfiring.  The  remedy  is  to  machine 
the  surfaces  of  the  sectors  and  walls  by  grinding  or  turning  in 
the  lathe.  Care  should  be  taken  in  this  operation  to  have  the 
interior  perfectly  smooth  and  the  sectors  perfectly  flush  with 
the  walls.  Repair  black  or  burnt  sectors  immediately  by  grind- 
ing or  sand  paper. 

Burnt  spots  or  blackened  surface  on  the  contact  sectors  pre- 
vent good  contact  between  roller  and  sector,  sectors  should 
show  a  bright,  shining  metallic  surface. 

Sometimes  the  insulation  warps  or  swells  above  the  contacts 
so  that  the  roller  jumps  over  the  contacts  without  touching 
them,  or  if  for  any  reason  that  contact  is  made  under  these 
conditions,  it  is  of  a  short,  period  and  results  in  a  poor  spark. 

Timers  often  make  good  contact  when  starting,  or  at  low 
speed,  and  misfire  badly  at  high  speed.  This  will  be  caused 
generally  by  the  contact  sectors  or  insulation  projecting  beyond 
one  another,  the  roller  has  time  to  make  good  contact  at  low 
speed  but  jumps  over  the  sector  at  high. 

The  roller  I  may  become  rough  or  develop  a  flat  stop  which 
will  cause  it  to  jump  over  the  contact  occasionally,  or  it  may 
become  loose  on  its  bearing  pin  J,  causing  intermittent  misfiring. 

The  wearing  or  loosening  of  pins  J  and  X  result  in  poor  con- 
tact. Should  pin  J  fall  out  of  the  lever  H,  the  roller  would  drop 
out  of  the  fork  and  cause  serious  damage.  This  has  happened 
in  two  cases  to  my  knowledge. 

Should  the  spring  G  weaken  or  break,  contact  will  be  made 
intermittently  at  high  speed,  and  no  contact  at  low.  In  this 
case  it  would  probably  be  impossible  to  start  the  engine.  In  case 
the  spring  breaks,  a  rubber  band  may  be  used  temporarily. 
Wire  connections  to  the  timer  should  be  examined  frequently 
as  the  continual  back  and  forth  movement  tends  to  twist  and 
loosen  the  wire.  Use  stranded  or  flexible  wire  for  these  con- 
nections, if  possible. 

Before  removing  the  timer  mark  the  hub  and  the  shaft  so 


240  GAS,  OIL  AND  STEAM  ENGINES 

that  the  hub  can  be  properly  replaced.  If  this  is  not  done  the 
engine  will  be  out  of  time  with  the  usual  results  of  hammer- 
ing or  power  loss. 

Should  the  gears  which  drive  timer  shaft  be  removed,  be  sure 
and  mark  the  teeth  of  both  gears  in  such  a  manner  that  there 
will  be  no  mistake  possible  in  reassembling  them.  Mark  a  tooth 
on  the  small  gear  by  scratching  or  with  a  center  punch  (the 
tooth  selected  should  be  in  mesh  with  the  large  gear).  Then 
mark  the  two  teeth  of  the  large  gear  that  lay  on  either  side  of 
the  marked  tooth  of  the  small  gear.  Thus  it  will  be  easy  to 
locate  the  proper  relative  position  of  the  two  gears  at  any 
time. 

(95)  High  Tension  Spark  Plug. 

The  high  tension  spark  plug  is  a  device  that  introduces  the 
spark  gap  and  spark  into  the  combustion  chamber,  and  at  the 
same  time  insulates  the  current  carrying  conductor  from  the 
cylinder  walls.  Since  the  voltage  of  the  jump  spark  current 
is  very  high  it  is  evident  that  the  insulation  of  the  plugs  must 
be  of  a  very  high  order  and  that  this  insulation  must  be  capable 
of  withstanding  the  high  temperature  of  the  combustion  cham- 
ber. A  cross-section  of  a  typical  plug  is  shown  by  Fig.  98,  to- 
gether with  its  connections  and  the  course  of  the  current,  the 
latter  being  shown  by  the  arrow  heads. 

The  electrode  B  through  which  the  current  enters  the  cylinder 
is  thoroughly  insulated  from  the  walls  by  the  porcelain  rod  C. 

The  porcelain  forms  a  gas  tight  joint  with  the  threaded 
metal  bushing  F  at  the  point  P,  the  tension  caused  by  the  elec- 
trode B  and  the  nut  I  holds  the  porcelain  firmly  on  its  seat  at  P. 

The  nut  is  supported  by  the  porcelain  shell  H  which  rests 
in  the  top  of  the  metal  bushing  F.  A  washer  L  is  inserted  be- 
tween H  and  F  to  insure  against  the  leakage  of  gas  from  the 
plug  should  a  leak  develop  at  P.  L  being  a  soft  washer  (usually 
asbestos)  allows  the  porcelains  C  and  H  to  expand  and  contract 
without  breaking.  A  packing  washer  or  gasket  is  also  placed 
at  the  point  where  the  electrode  B  passes  through  the  porcelain 
H.  This  is  the  washer  Q,  held  in  position  by  the  nut  I.  This 
washer  is  elastic  and  reduces  strain  on  porcelain  caused  by  the 
expansion. 

The  cylinder  wall  G  has  a  threaded  opening  R  into  which 

'the  plug  is  screwed,  the  threads  of  the  opening  corresponding 

with   the  threads   on   the   metal   sleeve   E.     The   plug  may  be 

removed  from  the  cylinder  for  examination  without  disturbing 


GAS,  OIL  AND  STEAM  ENGINES 


241 


the  adjustment  of  the  electrode  and  porcelains  by  unscrewing 
it  at  R. 

Allowing  the  current  to  jump  from  the  electrode  to  the  cyl- 
inder wall  via  the  metal  sleeve  saves  one  wire  and  connection, 
the  cylinder  and  the  frame  of  the  engine  serving  as  a  return 
path  for  the  current.  This  simplifies  the  wiring  and  minimizes 
the  danger  of  high  tension  short  circuits. 


Fig.    98.     Cross-Section    of   Typical    Spark    Plug. 

By  unscrewing  the  threaded  metal  bushing  F  it  is  possible 
to  examine  the  condition  of  the  porcelain  rod  C  at  the  point 
where  it  is  exposed  to  the  heat  of  the  cylinder.  This  inspection 
can  be  made  without  disturbing  the  packed  joints  at  L  or  Q. 

In  the  high  tension,  or  jump  spark  system,  the  spark  gap 
D-K  is  of  fixed  length,  hence  there  are  no  moving  parts  or 
contacts  within  the  cylinder  to  wear,  to  cause  leakage  of  gas, 
or  to  cause  a  change  in  the  timing.  This  advantage  is  offset 


242  GAS,  OIL  AND  STEAM  ENGINES 

to  some  degree  by  the  difficulty  experienced  in  maintaining  the 
insulation  of  the  high  tension  current. 

The  high  tension  current  leaves  the  spark  coil  M  at  the  bind- 
ing screw  N,  flows  along  the  wire  J,  and  enters  the  spark  plug 
at  the  binding  screw  A.  From  the  binding  post  the  current 
follows  the  central  electrode  B  to  its  terminal  at  D.  At  D  a 
break  in  the  circuit  occurs  which  is  called  the  spark  gap.  It 
is  at  this  point  that  the  spark  occurs,  the  current  jumping  from 
D  to  point  K  through  the  air.  Point  K  is  fastened  in  the 
threaded  metal  sleeve  E  which  is  in  turn  screwed  into  the  cyl- 
inder wall  G  or  ground.  From  the  ground  the  current  returns 
to  its  source  through  binding  post  O  to  the  coil.  The  spark 
therefore  occurs  inside  of  the  cylinder  wall  and  in  contact  with 


Fig.   99.     Bosch   Spark   Plugs 

the  combustible  charge,  at  the  point  marked  "spark"  in  the  cut. 

If  the  fuel,  lubricating  oil,  and  air  are  not  supplied  in  proper 
proportions,  soot  will  be  deposited  on  the  lower  surface  of  the 
porcelain,  and  as  soot  is  an  excellent  conductor  of  high  tension 
current,  the  current  will  follow  the  soot  rather  than  the  high 
resistance  of  the  spark  gap,  a  condition  that  will  result  in  mis- 
firing or  a  complete  stoppage  of  the  motor.  Carbonized  lubri- 
cating oil  or  moisture  have  the  same  effect. 

Preventing  the  deposits  of  soot,  moisture  and  carbonized  oil 
is  the  chief  object  of  plug  manufacturers,  many  of  whom  have 
brought  out  designs  of  merit.  In  fact  the  problem  of  elimina- 
tion of  soot  is  the  principal  cause  of  the  many  types  of  plugs 
now  on  the  market. 

While  many  plugs  differ  in  minor  refinement  of  detail  from 
the  typical  plug  shown,  the  connections  and  general  construe- 


GAS,  OIL  AND  STEAM  ENGINES  243 

tion  are  the  same  in  all  types,  the  spark  being  produced  in  a 
gap  of  fixed  length  which  is  insulated  from  the  cylinder. 

A  well  known  form  of  plug,  the  Bosch,  is  shown  by  Fig.  99 
a-b.  In  this  plug  a  special  material  known  as  Steatite  is  used 
instead  of  the  usual  porcelain.  The  three  external  electrodes 
surrounding  the  center  electrode  is  a  particularly  efficient  ar- 
rangement, especially  for  magnetos.  A  peculiar  form  of  pocket 
minimizes  the  soot  problem. 

As  porcelain  is  brittle  and  is  easily  broken  by  the  effects  of 
heat  or  blows,  mica  insulation  is  often  used  in  place  of  the 
porcelain.  The  central  core  of  a  mica  plug  is  formed  by  a 
stack  of  mica  washers,  which  are  held  in  place  by  the  central 
electrode  and  the  upper  lock  nuts. 

A  poorly  constructed  mica  plug  is  easily  destroyed  by  a 
weak,  stretching,  electrode,  or  by  an  overheated  cylinder.  The 
latter  causing  the  washers  to  shrink  and  admit  oil  between  the 
layers  of  mica  washers  causes  a  short  circuit.  As  soon  as  the 
mica  washers  loosen  and  separate,  they  should  be  forced  to- 
gether by  means  of  the  mica  lock  nuts  on  the  top  of  the  plug. 

If  by  any  reason  the  mica  core  becomes  saturated  with  oil, 
it  is  best  to  obtain  a  new  one,  as  it  is  almost  impossible  to 
remove  the  oil  by  simple  means  open  to  the  average  operator. 

The  chief  value  of  a  mica  plug  lies  in  its  toughness  and  me- 
chanical strength,  a  good  mica  plug  being  practically  indestruct- 
ible. 

When  heated,  porcelain  does  not  expand  at  the  same  rate  as 
the  metal  sleeves,  hence  in  poorly  designed  or  imperfect  plugs, 
heavy  strains  are  thrown  on  the  delicate  porcelains  which  causes 
them  to  crack.  When  a  crack  develops  it  provides  a  lodging 
place  for  soot  and  carbon  which  of  course  causes  a  short  circuit. 
Should  a  compression  leak  occur  through  faulty  packing  be- 
tween the  porcelain  and  sleeve,  it  should  be  immediately  tight- 
ened up  for  eventually  it  will  leak  enough  to  destroy  the  plug 
or  reduce  the  output  of  the  engine. 

When  ordering  a  plug  be  sure  that  you  know  the  size  and 
type  required  by  your  engine.  Some  engines  require  a  longer 
plug  to  reach  the  combustion  chamber  than  others.  Never  in- 
stall a  shorter  plug  than  that  originally  furnished  with  the  en- 
gine. Be  sure  that  the  plug  is  not  too  long  as  it  may  interfere 
with  the  action  of  the  valves  or  may  be  damaged  by  them. 
Plugs  are  furnished  with  several  threads  and  taps,  i.  e. : 

5^  inch  pipe  thread  (Generally  used  on  stationary  engines). 

Metric  Thread   (Generally  used  on  imported  autos). 


244  GAS,  OIL  AND  STEAM  ENGINES 

%  inch  A.  L.  A.  M.  Standard  (Used  on  Domestic  automobiles). 

Using  a  plug  in  a  hole  tapped  with  the  wrong  thread  will 
destroy  the  thread  in  the  cylinder  casting  and  cause  compression 
leaks. 

(96)  Care  of  Spark  Plug. 

Porcelains  are  often  broken  by  screwing  the  plug  too  tightly 
in  a  cold  cylinder,  as  the  cylinder  expands  when  heated  and 
crushes  the  frail  plug.  A  plug  installed  in  this  manner  is  dim- 
cult  to  remove  as  the  expanded  walls  grip  the  thread.  The 
plug  should  be  screwed  in  just  enough  to  prevent  the  leakage 
of  gas.  A  short  thin  wrench  should  "be  used  in  screwing  the 
plug  home  such  as  a  bicycle  wrench.  A  wrench  of  this  type 
is  so  short  that  it  will  be  almost  impossible  to  exert  too  much 
force,  and  will  be  thin  enough  to  avoid  any  possible  injury 
to  the  packing  nut.  Bad  leaks  may  be  detected  by  a  hissing 
sound  that  is  in  step  with  the  speed  of  the  engine,  small  leaks 
may  be  detected  by  pouring  a  few  drops  of  water  around  the 
joint.  If  a  leak  exists  bubbles  will  pass  up  through  the  water 
and  show  its  location. 

Plugs  are  more  easily  removed  from  a  cold  cylinder  than  a 
hot.  If  the  plug  sticks  when  the  engine  is  cold  and  is  impossi- 
ble to  remove  with  a  moderate  pressure  on  the  wrench  squirt  a 
few  drops  of  kerosene  around  the  threads.  Never  exert  any 
force  on  the  porcelain  or  insulation.  The  high  tension  cables 
should  be  connected  to  the  plugs  by  means  of  some  type  of 
"Snap  Terminal,"  such  terminals  may  be  had  from  automobile 
dealers. 

These  terminals  make  a  firm  contact  with  the  plug  and  do 
not  jar  loose  from  the  plug  by  the  vibration  of  the  engine.  They 
are  easily  disconnected  when  the  inspection  of  the  plug  becomes 
necessary,  and  are  generally  a  most  desirable  attachment. 

The  high  tension  cable  should  be  firmly  connected  to  the 
plug  terminal  under  all  circumstances.  A  loose  connection  will 
cause  misfiring  or  will  bring  the  engine  to  an  abrupt  halt.  If 
snap  terminals  are  not  used  the  plug  binding  screw  should  be 
screwed  down  tightly  on  the  wire.  When  making  connections 
see  that  the  wire  is  bright  and  clean,  and  that  frayed  ends  of 
the  wire  do  not  project  beyond  the  plug  and  make  contact  with 
other  parts  of  the  engine. 

A  large  percentage  of  high  tension  ignition  troubles  are  due 
to  short  circuits  in  the  spark  plug  which  are  generally  caused 
by  deposits  on  the  surface  of  the  plug  insulation.  Soot  or  oil 


GAS,  OIL  AND  STEAM  ENGINES  245 

may  be  removed  from  the  plug  by  scrubbing  the  porcelain  and 
the  interior  of  the  chamber  with  gasoline  applied  by  a  tooth 
brush.  Examine  the  plug  for  cracks,  and  if  any  are  found,  re- 
place the  porcelain  or  throw  the  plug  away.  A  cracked  por- 
celain is  always  a  cause  of  trouble. 

To  test  a  plug  for  short  circuits,  remove  it  from  the  cylinder, 
reconnect  the  wire,  and  lay  the  sleeve  of  the  plug  on  some 
bright  metal  part  of  the  engine  in  such  a  way  that  only 
the  threaded  portion  is  in  contact  with  the  metal  of  the 
engine.  Close  the  switch  and  see  if  sparks  pass  through 
the  gap.  If  no  sparks  appear,  and  if  the  coil  is  operating  prop- 
erly, clean  the  plug.  As  an  additional  test  for  the  condition  of 
the  coil,  hold  the  end  of  the  high  tension  cable  about  J4  mcn 
from  the  metal  of  the  engine  while  the  coil  is  operating.  If  a 
heavy  discharge  of  sparks  takes  place  between  the  end  of  the 
cable  and  the  metal  of  the  engine,  the  coil  is  in  good  condition. 

If  a  partial  short  circuit  exists,  the  spark  at  the  gap  will  be 
weak  and  without  heat;  the  result  will  be  intermittent,  or  mistfir- 
ing  with  a  loss  of  power.  Moisture  in  the  cylinder  is  a  common 
cause  of  plug  short  circuits,  the  moisture  coming  from  leaks 
in  the  water  jacket  or  from  the  condensation  of  gases  in  a  cold 
cylinder.  A  drop  of  water  may  bridge  the  spark  gap,  allowing 
the  current  to  flow  from  one  electrode  to  the  other  without 
causing  a  spark. 

If  a  cloud  of  bluish  white  smoke  has  been  issuing  from  the 
exhaust  pipe  before  the  misfiring  started,  you  will  probably 
find  that  the  trouble  is  due  to  sooted  or  short  circuited  plug. 

The  remedy  is  to  decrease  the  amount  of  lubricating  oil  fed 
to  the  cylinder. 

When  a  magneto  is  used  the  intense  heat  of  the  spark  causes 
minute  particles  of  metal  to  be  torn  from  the  electrodes  and 
deposited  on  the  insulation  as  a  fine  metallic  dust.  This  will 
of  course  cause  a  short  circuit  and  must  be  removed.  Short 
circuits  are  sometimes  caused  by  the  magneto  current  melting 
the  electrodes  and  dropping  small  beads  of  the  metal  between 
the  conductors.  All  metallic  particles  should  be  removed  from 
the  plug. 

While  a  spark  plug  may  show  a  fair  spark  in  the  open  air 
test,  it  will  not  always  produce  a  satisfactory  spark  in  the  cyl- 
inder on  account  of  the  increased  resistance  of  the  spark  gap 
due  to  compression. 

Compression  increases  the  resistance  of  the  spark  gap  enor- 
mously and  thin,  highly  resisting  carbon  films  that  would  cause 


246  GAS,  OIL  AND  STEAM  ENGINES 

very  little  leakage  in  the  open  air  will  entirely  short  circuit  the 
gap  under  high  pressure,  the  current  taking  the  easiest  path 
which  in  the  latter  case  is  the  carbon  deposit. 

In  order  to  produce  conditions  in  the  open  air  test  similar 
to  those  in  the  cylinder  we  must  devise  some  method  of  in- 
creasing the  resistance  of  the  spark  gap  in  the  open  air  above 
any  possible  resistance  that  could  be  offered  by  the  carbon  film. 

Placing  a  sheet  of  mica  or  hard  rubber  between  the  electrodes, 
or  in  the  spark  gap,  will  increase  the  resistance  to  the  required 
degree.  If  the  spark  plug  is  in  good  condition  the  spark  will 
jump  from  the  insulated  terminal  to  the  shell  when  the  mica 
is  in  the  spark  gap,  but  if  a  short  circuit  exists  the  current  will 
go  through  it  without  causing  a  spark.  It  is  assumed  that  the 
battery  and  coil  are  in  good  condition  when  making  the  above 
test. 

If  the  electrodes  or  spark  points  are  dirty  they  should  be 
cleaned  with  fine  sand  paper,  special  att-ention  being  paid  to 
the  surfaces  from  which  the  spark  issues.  When  reassembling 
the  plug,  see  that  all  of  the  washers  and  gaskets  are  replaced 
and  that  the  length  of  the  spark  gap  is  unchanged.  A  little 
change  in  the  spark  gap  may  make  a  great  change  in  the  spark. 
A  good  spark  is  blue  white  with  a  faint  reddish  flame  sur- 
rounding it.  When  the  discharge  is  intermittent  or  sputters  in 
all  directions,  either  the  coil  or  the  plug  are  partially  short  cir- 
cuited. Always  have  a  spare  plug  on  hand. 

Ordinarily  the  length  of  the  gap  or  the  distance  between  the 
electrodes  should  be  about  3*2  inch  for  batteries,  and  a  trifle  less 
for  magnetos.  A  silver  dime  is  a  good  gauge  for  the  gap.  If 
the  engine  misfires  with  the  coil  and  batteries  in  good  condi- 
tion, try  the  effects  of  shortening  the  gap  a  trifle,  usually  this 
will  remedy  the  difficulty.  Exhausted  batteries  may  be  made 
operative  temporarily  by  closing  up  the  plug  gap  to  1/64  inch  or 
even  less.  Shortening  the  gap  increases  the  heat  of  the  spark 
and  nothing  is  gained  by  having  it  over  ^2  inch. 

Almost  all  high  tension  magnetos  have  visible  safety  spark 
gaps  that  show  instantly  the  presence  of  an  open  circuit  in  the 
secondary  or  high  tension  circuit.  If  an  open  circuit  exists, 
a  stream  of  sparks  will  flow  across  the  safety  spark  gap  at  low 
speed. 

To  determine  the  cylinder  that  is  misfiring  in  a  four  cylinder 
engine  proceed  as  follows: 

Remove  cover  on  spark  coil,  and  hold  down  one  vibrator 
spring  firmly  against  the  core  while  the  engine  is  running. 


GAS,  OIL  AND  STEAM  ENGINES  247 

If  the  engine  speed  is  not  decreased  by  cutting  this  coil  out 
of  action,  it  is  probable  that  this  is  the  coil  connected  to  the 
misfiring  cylinder.  Now  release  this  vibrator  and  proceed  to 
the  next  coil,  and  hold  its  vibrator  down.  If  this  decreases  the 
speed  of  the  engine  you  may  be  sure  that  the  first  coil  is  in  the 
defective  circuit.  If  the  vibrator  buzzes  on  the  coil  under  in- 
spection the  trouble  will  be  found  in  the  plug. 

Cutting  out  a  coil  connected  to  an  active  cylinder  decreases 
the  speed  of  the  engine.  Cutting  out  the  coil  connected  with  a 
dead  cylinder  makes  no  difference. 

(97)  Magnetos. 

A  magneto  is  a  device  that  converts  the  mechanical  energy 
received  from  the  engine  into  electrical  energy,  the  electricity 
thus  produced  being  used  to  ignite  the  charge  in  the  engine. 
This  appliance  does  away  with  all  of  the  troubles  incident  to 
a  rapidly  deteriorating  chemical  battery  and  produces  a  much 
hotter  and  uniform  spark.  A  magneto  is  especially  desirable 
with  multiple  cylinder  engines  where  the  demand  for  current 
is  almost  continuous,  as  the  amount  of  current  delivered  by 
the  magneto  has  no  effect  on  its  life  or  upon  the  quality  of  the 
spark. 

The  principal  parts  of  the  generating  system  of  the  magneto 
are  the  magnets,  the  armature,  the  armature  winding,  and  the 
current  collecting  device,  of  which  the  armature  and  its  wind- 
ings are  the  rotating  parts.  The  production  of  current  in  the 
magneto  is  the  result  of  moving  or  rotating  the  armature  coil 
in  the  magnetic  field  of  force  of  the  magnets.  When  any 
conductor  is  moved  in  a  space  that  is  under  the  influence  of  a 
magnet  a  current  is  generated  in  the  conductor  which  flows  in  a 
direction  perpendicular  to  the  direction  of  motion.  The  value 
of  the  current  thus  generated  depends  on  the  strength  of  the 
magnetic  field,  the  speed  with  which  it  is  cut,  and  the  number 
of  conductors  cutting  it  that  are  connected  in  series.  Roughly, 
the  voltage  is  doubled,  with  an  increase  of  twice  the  former 
speed,  and  with  all  other  things  equal,  the  voltage  is  doubled 
by  doubling  the  number  of  conductors  connected  in  series. 

By  employing  powerful  magnets,  and  a  large  number  of  con- 
ductors (turns  of  wire)  on  the  armature  it  is  possible  to  ob- 
tain sufficient  voltage  for  the  ignition  system  at  a  compara- 
tively low  speed.  The  number  of  amperes  delivered  depends 
principally  upon  the  internal  resistance  of  the  armature  and  the 
external  circuit,  and  not  on  the  number  of  conductors,  nor 


248  GAS,  OIL  AND  STEAM  ENGINES 

directly  upon  the  strength  of  the  field.  For  this  reason,  low 
voltage  machines  f'Jiat  are  intended  to  deliver  a  great  amperage 
have  only  a  few  conductors  of  large  cross  section,  while  high 
tension  machines  have  a  great  number  of  conductors  of  small 
size.  In  all  cases  the  magneto,  or  ignition  dynamo  must  be 
considered  simply  as  a  generator  of  current  in  the  same  way 
that  a  battery  is  a  source  of  current  since  the  current  generated 
by  them  is  utilized  in  precisely  the  same  way. 

The  class  of  ignition  system  on  which  the  magneto  is  used 
determines  the  class  of  the  magneto.  The  low  tension  mag- 
neto is  used  principally  for  the  make  and  break  system, 
although  it  is  sometimes  used  in  connection  with  a  high  ten- 
sion spark  coil  or  transformed  in  the  same  way  that  a  bat- 
tery is  used  with  a  vibrator  coil.  The  high  tension  magneto  is 
used  exclusively  with  the  jump  spark  system  and  high  tension 
spark  plug. 

These  classes  are  again  subdivided  into  the  direct  and  alter- 
nating current  divisions,  depending  on  the  character  of  the  cur- 
rent furnished  by  the  magneto.  Briefly  a  continuous  current  is 
one  that  flows  continually  in  one  direction  while  an  alternating 
current  periodically  reverses  its  direction  of  flow.  As  the  alter- 
nating current  magneto  is  the  most  commonly  used  type,  we 
will  confine  our  description  to  this  class  of  magneto.  The 
alternating  current  magneto  is  much  the  simplest  form  of  ma- 
chine as  it  has  no  commutator,  complicated  armature  winding, 
nor  field  magnet  coils,  and  in  some  types  the  brushes  and 
revolving  wire  are  eliminated. 

As  the  magnetic  flux  of  an  alternating  magneto  is  changed 
in  value,  that  is  increased  and  decreased,  twice  per  revolution, 
it  follows  that  the  current  changes  its  direction  twice  for  every 
revolution  of  the  armature.  Each  change  in  the  direction  of 
current  flow  is  called  an  alternation. 

The  voltage  developed  in  each  alternation  or  period  of  flow 
is  not  uniform,  the  voltage  being  low  at  the  start  of  the  alter- 
nation, rapidly  increasing  in  voltage  until  it  is  a  maximum  at 
the  middle,  and  then  rapidly  decreasing  to  zero,  from  which 
point  the  current  reverses  in  direction.  As  we  have  two  such 
alternations,  in  a  shuttle  type  magneto,  per  revolution  we  have 
two  points  at  which  the  maximum  voltage  occurs;  that  is  in  the 
center  of  each  alternation.  These  high  voltage  points  are  called 
the  peak  of  the  wave  and  consequently  the  sparking  devices 
should  operate  at  the  peak  of  the  wave  or  at  the  point  of  high- 
est voltage.  The  spark  therefore  should  occur  when  the  shuttle 


GAS,  OIL  AND  STEAM  ENGINES  249 

or  inductors  are  at  a  oertain  fixed  point  in  the  revolution  at 
which  point  the  peak  of  the  wave  occurs.  The  peak  of  the 
wave  occurs  when  the  shuttle  is  being  pulled  or  turned  away 
from  the  magnets. 

In  what  is  known  as  the  "shuttle  type"  alternating  current 
magneto,  the  generating  coil  is  wound  in  the  opening  of  an 
"H"  type  armature.  This  iron  armature  'core  is  fastened  rigidly 
to  the  driving  shaft  and  revolves  with  it.  As  the  armature 
revolves,  it  is  necessary  to  collect  the  current  that  is  generated 
by  means  of  a  brush  that  slides  on  a  contact  button  Bf  the 
button  being  connected  to  one  end  of  the  winding. 

(98)  Low  Tension  Magneto. 

The  winding  of  the  low  tension  magneto  consists  of  a  few 
turns  of  very  heavy  wire  or  copper  strip,  one  end  of  which 
is  grounded  to  the  armature  shaft  and  the  other  passing 
through  the  hollow  shaft  from  which  it  is  insulated.  The  end 
of  the  insulated  wire  is  connected  to  the  contact  button  (B) 
on  which  the  current  collecting  brush  presses.  As  one  end  of 
the  winding  is  grounded,  one  brush,  and  one  connecting  wire  is 
saved  as  the  current  returns  to  the  magneto  through  the  frame 
of  the  magneto.  As  the  shuttle  revolves  between  the  magnet 
poles  the  magnetism  is  caused  to  alternate  through  the  iron  of 
the  armature,  thus  causing  the  current  to  alternate  in  direction 
and  fluctuate  in  value. 

Since  there  are  only  two  points  at  which  the  maximum  cur- 
rent can  be  collected  during  a  revolution  with  the  alternating 
current  magneto,  it  is  necessary  to  drive  it  positively  through 
gears,  or  a  direct  connection  to  the  shaft  so  that  this  maximum 
point  of  voltage  will  always  occur  at  the  same  point  in  regard  to 
the  piston  position.  If  it  is  driven  by  belt  without  regard  to  the 
position  of  the  piston,  it  is  likely  that  there  will  be  many  times 
that  the  voltage  is  zero  or  too  low  in  value  when  the  spark  is 
required  in  the  cylinder.  Alternating  current  magnetos  must 
be  positively  driven,  and  the  armature  must  be  connected  to  the 
engine  so  that  the  peak  of  the  wave  occurs  at,  or  a  little  before 
the  end  of  the  compression  stroke. 

With  this  type  of  magneto  the  only  point  .that  is  likely  to 
give  trouble  is  the  point  at  which  the  brush  makes  contact  with 
the  contact  button.  If  the  brush  should  stick  or  not  make  con- 
tact, or  if  the  button  is  dirty  or  rusty,  the  current  will  not 
flow;  this  point  should  always  be  given  attention.  Outside 


250  GAS,  OIL  AND  STEAM  ENGINES 

of  this  the  only  attention  necessary  is  to  keep  the  bearings  oiled 
Fig.  101  and  Fig.  102  show  the  Sumter  low  tension  magneto  as 
arranged  for  make  and  break  ignition.  The  armature  and  its 
connections  are  of  exactly  the  same  type  as  that  shown  in  the 
previous  diagram.  The  magnets  and  frame  are  arranged  to 
tilt  back  and  forth  so  that  the  peak  of  the  wave  will  occur  at 
the  advanced  and  retarded  positions  of  the  igniter.  This  ar- 


Fig.    101.  Sumter    Magneto   Advanced.     Fig.    102.  Sumter    Magneto    Retarded. 


rangement  allows  the  full  voltage  of  the  magneto  to  be  obtained 
at  any  point  within  the  range  of  the  ignitor,  an  important  item 
when  starting  the  engine  or  running  at  low  speed.  When 
mounted  on  the  engine,  as  shown  by  Fig.  103,  the  magnets  are 
provided  with  an  operating  rod  that  is  marked  "start"  and 
"run."  When  the  pin  on  the  engine  bed  is  engaged  under 
"start,"  the  magneto  is  retarded,  when  the  pin  is  under  "run" 
it  is  advanced.  A  number  of  intermediate  points  are  provided 
at  which  the  operating  arm  is  held  fast  by  tooth  engagements 
as  shown  in  the  slotted  handle.  As  shown  in  the  illustration 
the  magneto  is  fully  advanced.  The  gears  by  which  the  mag- 


GAS,  OIL  AND  STEAM  ENGINES 


251 


neto  is  driven  are  clearly  shown  in  the  cut,  the  ratio  between 
the  gear  on  the  crank  shaft  and  that  on  the  magneto  shaft  be- 
ing exactly  2  to  1.  One  lead  is  carried  to  the  make  and  break 
igniter  in  the  cylinder  head,  the  current  being  returned  through 
the  bed  of  the  engine.  The  same  make  of  magneto  is  shown 


mounted  on  a  vertical  engine  in  Fig.  104.  In  this  case  the 
magneto  is  positively  driven  from  the  crank  shaft  of  the  engine 
by  a  chain.  The  single  conductor  running  from  the  magneto 
to  the  cylinder  heads  is  clearly  shown.  To  start  the  engine, 
the  igniter  is  set  in  the  usual  manner  and  the  magneto  tilted  to 
starting  position,  as  shown  in  the  illustration.  The  engine  is 
then  started  in  the  usual  manner  and,  when  running,  the  igniter 
is  changed  to  running  position,  and  the  magneto  is  tilted  out- 


252  GAS,  OIL  AND  STEAM  ENGINES 

wardly.  It  is  not  important  which  is  changed  first,  the  magneto 
or  the  igniter.  It  is  easy  to  remember  the  "starting"  and  run- 
ning "position"  of  the  magneto,  the  running  position  always  be- 
ing that  in  which  the  magnetos  are  tilted  in  the  direction 
opposite  to  that  in  which  the  engine  runs. 

(99)  Care  of  Low  Tension  Magnetos. 

(1)  Avoid  setting  a  magneto  on  an  iron  or  steel  plate,  unless 
stated  otherwise   in  the  manufacturer's   directions,   as  in   some 
makes  the  magnetism  will  be  short  circuit  by  iron  or  steel  and 
will  reduce  the  output. 

(2)  Do  not  jar  magnets   or  magneto  unnecessarily,   for  this 
tends  to  weaken  the  magnets. 

(3)  Never  remove  the  magnets  if  it  can  possibly  be  avoided. 
If  this  must  be  done,  mark  the  magnets  and  gears  so  that  they 
may  be  replaced  in  exactly  the  same  position.     If  your  mag- 
neto refuses  to  generate  after  reassembling  it  is  probable  that 
they  are  reversed  in  position  or  that  the  magnetism  has  been 
knocked  out  of  them  while  off  of  the  magneto. 

(4)  As  soon  as  the  magnets  are  removed,  or  better  before, 
place  a  plate  of  iron  or  steel  across  both  ends  of  the  magnet. 
Don't  leave  the  magnets  without  this  keeper  for  any  length  of 
time  or  they  will  lose  their  magnetism.     The  best  plan  is  to 
leave  the  magnets  alone. 

(5)  Remember  that  the  running  clearance  between  the  mag- 
nets and  armature  is  very  small,  only  a  few  thousandths  of  an 
inch,  and  that  any  error  in  replacing  the  bearings  in  their  proper 
position  will  cause  the  armature  to  bind  in  the  tunnel.     Handle 
armature  carefully  and  do  not  lay  it  in  a  dirty  place  as  a  bent 
shaft  or  grit  in  the  armature  tunnel  will  fix  it  permanently. 

(6)  Most  all  magnetos  are  practically  water  proof,  but  don't 
experiment  with  the  hose. 

(7)  Make    all    connections    firmly    and    have    the    wire    clean 
under  the  binding  posts. 

(8)  Only  a  few   drops   of  oil   are   needed   at  long  intervals, 
don't  neglect  to  oil  them,  but  above  all  do  not  drown  them  with 
oil. 

(9)  Examine  the  brush  occasionally  and  clean  off  all  oil  and 
dirt. 

(10)  When    replacing   the    magneto    on    the    engine   after   its 
removal  see  that  the  gears  are  meshed  in  the  former  position. 
Best  to  mark  the  teeth  before  removal. 


GAS,  OIL  AND  STEAM  ENGINES  253 

(100)  High  Tension  Magnetos. 

The  "true"  high  tension  type  magneto  is  complete  in  itself, 
requiring  no  jump  spark  coil  nor  timer,  the  high  tension  cur- 
rent being  generated  directly  in  the  coils  carried  by  the  arma- 
ture. This  arrangement  reduces  the  wiring  problem  to  a  mini- 
mum, as  the  only  wires  required  are  those  leading  directly  to 
the  spark  plugs,  and  one  low  tension  wire  connecting  the  cut- 
out switch  used  for  stopping  the  engine. 

The  armature  of  this  type  of  magneto  carries  two  independ- 
ent windings,  one  of  a  few  turns  of  coarse  wire  called  the  pri- 
mary coil,  and  the  other  consisting  of  thousands  of  turns  of 
extremely  fine  wire  called  the  secondary  coil.  It  is  in  the  latter 


Fig.    105.     Single    Cylinder  High    Tension   Bosch   Magneto. 

coil  that  the  high  tension  current  is  generated.  The  tinier  is 
connected  directly  to  the  armature  shaft,  and  is  an  integral  part 
of  the  magneto.  All  primary  connections  are  therefore  made 
within  the  magneto. 

Belts  or  friction  drives  cannot  be  used  with  this  type  of 
magneto. 

As  there  are  no  vibrators  or  independent  coils  used,  the  spark 
occurs  exactly  at  the  instant  that  the  timer  operates  or  breaks 
the  primary  circuit.  It  will  be  noted  that  the  spark  is  produced 
with  this  magneto  when  the  primary  circuit  is  broken  by  the 
timer,  instead  of  made  as  is  the  case  with  battery  coils,  or  coils 
used  with  low  tension  magnetos.  There  is  no  lag  and  conse- 
quently the  time  of  ignition  is  not  affected  by  variations  in  the 
engine  speed,  which  requires  an  advance  and  retard  of  the  spark 
with  batteries  and  vibrator  coils. 


254  GAS,  OIL  AND  STEAM  ENGINES 

When  used  with  multiple  cylinder  engines  the  high  tension 
magneto  is  provided  with  a  distributor,  which  connects  the  high 
tension  current  with  the  different  cylinders  in  their  proper  firing 
order.  The  timer  determines  the  time  at  which  the  spark  is 
to  occur  and  the  distributor  determines  the  cylinder  in  which 
the  spark  is  to  take  place. 

The  sparks  delivered  by  the  high  tension  magneto  are  true 
flames  or  arcs  of  intense  heat,  and  exist  in  the  spark  gap  for  an 
appreciable  length  of  time.  It  is  evident  that  such  flames  pos- 
sess a  much  greater  igniting  value  than  instantaneous  static 
spark  delivered  by  the  high  tension  spark  coil  used  with  the  bat- 


Fig.    106.     Connecticut    High    Tension    Magneto. 

tery  or  operated  by  the  low  tension  magneto,  and  are  capable 
of  firing  much  weaker  mixtures. 

Like  low  tension  magnetos,  the  true  high  tension  type  may  be 
of  either  the  inductor  or  shuttle  wound  class.  All  high  tension 
magnetos  are  positively  connected  or  geared  to  the  engine  in 
such  a  manner  that  there  is  a  fixed  relation  between  time  of  the 
current  impulse  produced  by  the  magneto  and  the  firing  posi- 
tion of  the  engine  piston. 

The  current  is  generated  on  the  same  principle  as  in  the 
low  tension  shuttle  type;  that  is,  by  a  coil  of  wire  revolving 
in  the  magnetic  field  established  by  permanent  magnets. 


GAS,  OIL  AND  STEAM  ENGINES 


255 


During  each  revolution  of  the  armature,  two  sparks  are  pro- 
duced at  an  angle  of  180°  from  each  other. 

The  advance  and  retard  of  the  spark  is  obtained  by  means 
of  the  timing  lever  which  shifts  the  timer  housing  back  and 
forth  which  results  in  the  primary  current  being  interrupted 
earlier  or  later  in  the  revolution  of  the  armature. 

The  timing  lever  can  turn  through  an  angle  of  40°  measured 


Fig.    107.     Longitudinal   Section   Through   Bosch   High   Tension   Magneto. 

on  the  armature  spindle,  and  the  angle  of  advance  for  multiple 
engines  is  as  follows: 

Advance  for  1  cylinder    40° 

Advance  for  2  cylinders  40° 

Advance  for  3  cylinders  50° 

Advance  for  4  cylinders  40° 

Advance  for  6  cylinders  27° 

A  timer  is  used  with  the  magneto  on  a  "jump  spark"  system 
in  the  same  way  as  with  a  battery,  providing  a  vibrating  coil 
is  used. 

In  one  type  of  magneto  the  Connecticut,  the  coil  is  part 
-of  the  magneto,  and  is  fastened  to  the  magneto  frame.  This 
type  of  magneto  uses  a  non-vibrating  coil,  and  produces  but 
a  single  spark  each  time  the  primary  circuit  is  broken  by  the 
magneto  timer.  As  the  timer  on  this  type  is  driven  by  the 


256  GAS,  OIL  AND  STEAM  ENGINES 

magneto  shaft,  it  is  evident  that  the  magneto  must  be  "timed" 
with  the  engine,  or  must  have  its  armature  shaft  connected 
to  the  shaft  of  the  engine  in  such  a  manner  that  the  timer  con- 
tact is  broken,  and  the  single  spark  produced  at  the  instant 
that  ignition  is  required  in  the  cylinder. 

Unlike  the  dynamo,  the  alternating  current  magneto  can- 
not be  used  with  a  storage  battery,  the  alternating  current  pro- 
ducing no  chemical  change  in  the  electrodes  of  the  battery. 

The  Bosch  high  tension  magneto  is  a  typical  high  tension 
magneto  having  the  primary  and  secondary  windings  wound 
directly  on  the  armature  shaft,  there  being  no  external  sec- 
ondary coil.  The  end  of  the  primary  winding  is  connected 
to  the  plate  (1)  Fig.  107,  which  conducts  the  current  to  the 


Four  Cylinder  "D4"  High  Tension  Bosch  Magneto   Showing  Distributor. 

platinum  screw  of  the  circuit  breaker  (3).  Parts  (2)  and  (3) 
are  insulated  from  the  breaker  disc  (4),  which  is  in  electrical 
contact  with  the  armature  core  and  frame.  When  the  circuit 
breaker  contacts  are  together  the  primary  winding  is  short 
circuited,  and  when  they  are  separated  the  current  is  broken 
and  the  spark  oecurs.  The  breaker  contacts  are  simply  two 
platinum  pointed  levers  that  are  separated  and  brought  to- 
gether by  the  action  of  a  cam  as  they  revolve.  A  condenser 
(8)  is  provided  for  the  circuit  breaker  to  suppress  the  spark 
and  to  increase  the  rapidity  of  the  "break." 

The  secondary  winding  of  fine  wire  is. a  continuation  of  the 
primary  winding,  and  the  secondary  is  wound  directly  over  the 
primary.  The  outer  end  of  the  secondary  connects  with  the 


GAS,  OIL  AND  STEAM  ENGINES 


257 


slip  ring  (9)  on  which  slides  the  carbon  brush  (10),  which  con- 
ducts the  high  tension  current  from  the  armature.  This  brush 
is  insulated  from  the  frame  by  the  insulation  (11).  From  (10) 
the  current  is  led  through  the  bridge  (12)  through  the  carbon 
brush  (13)  to  the  distributer  brush  (15).  Metal  segments  are 
imbedded  in  the  distributor  (16),  the  number  of  which  corre- 
sponds to  the  number  of  cylinders.  As  the  brush  rotates,  it 
makes  consecutive  contact  with  each  of  the  segments  in  turn 
and  therefore  leads  the  current  to  the  cylinders  in  their  firing 
order.  Wires  from  the  cylinders  are  connected  to  sockets  that 
in  turn  connect  with  the  segments.  The  disc  driving  the  dis- 


r 


— _    Primary  winding 

Secondary  winding 

—  -    Frame 


breaker  di 


Fig.    108.     Bosch    High   Tension    Circuit. 

tributor  brush  (15)  is  geared  from  the  armature  shaft  in  such 
a  way  that  the  armature  turns  twice  for  every  revolution  of  the 
distributor,  when  four  cylinders  are  fired,  and  three  times  -for 
the  distributors  once  when  six  cylinders  are  fired. 

The  voltage  of  the  current  generated  in  the  secondary  coil 
by  the  rotation  of  the  armature  is  increased  by  the  interrup- 
tion of  the  primary  circuit  caused  by  the  opening  of  the  contact 
breaker. 

At  the  instant  of  interruption  of  the  primary  circuit  the  high 
tension  spark  is  produced  at  the  spark  plug. 

As  the  spark  must  occur  in  the  cylinder  of  the  engine  at  a 
certain  position  of  the  piston,  it  is  necessary  that  the  interrupter 
act  at  a  point  corresponding  to  a  definite  position  of  the  piston, 
consequently  this  type  of  magneto  must  be  driven  positively 


258  GAS,  OIL  AND  STEAM  ENGINES 

from  the  motor  by  means  of  gears,  or  directly  from  the  shaft. 

These  magnetos  run  in  only  one  direction.  This  running 
direction  should  be  given  when  magneto  is  ordered,  as  being 
"clockwise"  or  "counter-clockwise"  when  looking  at  the  driving 
end  of  the  magneto. 

The  magneto  for  the  single  and  double  cylinder  engines  has 
no  distributor,  the  high  tension  current  being  led  directly  from 
the  armature. 

The  circuit  diagram  of  the  Bosch  four  cylinder  magneto  is 
shown  by  Fig.  108,  the  winding  and  plug  connections  being 
clearly  shown.  When  connecting  the  magneto  care  should  be 
taken  to  have  the  distributor  and  plug  connections  arranged  so 
that  the  cylinders  will  fire  in  the  proper  order. 

(101)  Bosch  Oscillating  High  Tension  Magneto. 

The  oscillating  type  of  magneto  is  used  on  slow  speed  heavy 
duty  engines  that  move  too  slowly  for  the  ordinary  type  of 
magneto.  In  the  oscillating  type  the  armature  is  given  a  short 
angular  swing  by  the  action  of  a  tripping  device  operated  by 
the  engine  which  results  in  an  intense  spark  at  the  lowest 
speeds. 

Magneto  type  "29"  is  constructed  with  two  powerful  steel 
magnets,  while  magneto  type  "30"  is  provided  with  three;  an 
armature  of  the  shuttle  type  is  arranged  to  oscillate  between 
their  poleshoes. 

The  magneto  is  actuated  by  a  rotating  cam  or  other  suitable 
device,  which  moves  the  armature  30°  from  its  normal  position 
whenever  ignition  is  required.  To  permit  this  movement,  a 
trip  lever  is  mounted  upon  the  tapered  end  of  the  armature 
shaft,  this  trip  lever  being  held  in  a  definite  position  by  the 
tension  of  the  spring  or  springs  1.  The  trip  lever  is  only  sup- 
plied when  specially  ordered,  but  each  magneto  is  provided 
with  the  necessary  springs  and  spring  bolts. 

When  the  trip  lever  is  moved  from  its  normal  position  by 
the  operating  mechanism,  the  springs  are  extended,  and  when 
the  operating  mechanism  releases  the  trip  lever,  the  later  re- 
turns the  trip  lever  and  armature  to  their  normal  position,  this 
movement  resulting  in  the  production  of  a  sparking  current  in 
the  armature  winding. 

The  winding  of  the  armature  is  composed  of  two  parts,  one 
being  the  primary  winding,  which  consists  of  a  few  turns  of 
heavy  wire,  and  the  other  the  secondary  winding,  which  con- 
sists of  many  turns  of  fine  wire. 


GAS,  OIL  AND  STEAM  ENGINES  259 

The  tension  of  the  current  produced  by  the  oscillation  of 
the  armature  is  increased  by  closing  the  primary  circuit  at  a 
certain  position  in  its  movement,  and  then  interrupting  it  by 
means  of  the  breaker.  At  the  moment  of  the  interruption, 
an  arc-like  spark  is  formed  at  the  spark  plug  and  ignition  occurs. 

On  cam  shaft  (c)  two  cams  are  mounted  side  by  side.  One 
of  these  cams  (a)  is  to  be  used  for  starting  the  motor,  or  for 
the  retarded  spark  position,  while  the  second  (b)  is  to  be  used 
for  operation,  or  for  the  full  advance  position.  These  cams 
are  mounted  on  a  sleeve,  which  may  be  moved  longitudinally 
on  the  shaft,  so  that  the  trip  lever  may  be  operated  by  cam 
(a)  or  cam  (b)  as  desired.  The  sleeve  is  caused  to  rotate  with 
the  shaft  by  a  key.  Between  the  cam  (b)  and  a  fixed  collar  (f) 
a  spiral  spring  is  arranged,  which  tends  to  maintain  the  sleeves 


Fig.    109.     Elevation   of   Bosch   Oscillating  Magneto   for   Slow    Speed   - 
Engines.      High    Tension    Type. 

in  the  position  when  the  cam  (b)  is  in  operation.  A  stop  collar 
is  also  provided  to  limit  the  movement  of  the  sleeve  beyond  this 
full  advance  position.  Over  this  collar  is  fitted  a  hand  wheel, 
which,  in  the  position  illustrated  in  the  diagram,  acts  together 
with  the  collar  as  a  stop.  Around  the  collar  is  a  circular  key- 
way,  and  a  brass  bolt  is  located  in  the  hand  wheel  to  lock  into 
this  keyway  when  the  hand  wheel  is  pushed  into  the  position 
indicated  by  the  dotted  lines.  This  movement  of  the  wheel 
forces  the  cam  sleeve  forward,  and  brings  the  retarded  cam  (a) 
into  the  operating  position  to  permit  the  engine  to  be  started. 

(102)  The  Mea  High  Tension  Magneto. 

The  low  tension  winding  of  the  ordinary  type  of  magneto  is 
short-circuited  by  a  breaker  which  opens  at  certain  points  of 


260 


GAS,  OIL  AND  STEAM  ENGINES 


each  revolution  with  the  result  that  a  high  voltage  is  generated 
across  the  high  tension  winding  at  the  moment  of  the  break, 
and  a  spark  produced  across  the  spark  gap  in  the  cylinder  to 
which  it  is  connected.  The  quality  of  this  spark,  or  in  other 
words  the  heat  value,  depends  among  other  factors  upon  the 
particular  position  of  the  armature  in  relation  to  the  magnetic 
field  at  the  moment  the  spark  is  produced.  As  the  armature  in 
this  type  of  magneto  is  in  a  favorable  position  for  obtaining  a 


Fig.    110.     Diagram    of    Oscillating    Magneto,    Showing    Cam    and    Trigger 
Arrangement. 

spark  twice  every  revolution,  two  sparks  can  be  obtained  per 
revolution.  The  timing  of  the  spark  is  accomplished  by  open- 
ing the  breaker  earlier  or  later,  by  shifting  the  breaker  housing 
naturally  with  the  unavoidable  result  that  if  the  position  of  the 
magnetic  field  remains  stationary,  the  relative  position  between 
armature  and  field  at  the  moment  of  the  break  must  vary.  Since, 
however,  as  explained  above,  the  quality  of  the  spark  depends 
upon  this  relative  position,  it  is  apparent  that  a  good  spark, 


GAS,  OIL  AND  STEAM  ENGINES 


261 


can,  with  a  stationary  magnetic  field,  be  produced  only  at  one 
particular  timing. 

The    result    of    these    conditions    are    known    to    everybody 


Fig.   111.     Side   Elevation  of  "Mea"   Magneto,   Showing  the   Magnets,  and 
Cradle  in  Which  the  Magneto  Swings  When  Advanced  and  Retarded. 

familiar  with  automobiles.  They  are  the  difficulty  of  cranking 
a  motor  on  one  of  the  average  high  tension  magnetos,  if  the 
spark  is  fully  retarded,  and  of  operating  the  motor  on  the  mag- 


1    7f 


1  12      ,         4:  18    100 

Fig.    112.     Longitudinal    Section    of    "Mea"    High    Tension    Magneto. 

neto  at  very  low  speed,  particularly  when  it  is  overloaded,  as 
for  example,  in  hill  climbing.  Attempts  have  therefore  been 
made  to  obtain  the  spark,  independent  of  the  timing,  always  at 
the  same  favorable  position  of  the  armature. 


262  GAS,  OIL  AND  STEAM  ENGINES 

The  distinct  innovation  and  improvement  incorporated  in  the 
Mea  magneto  consists  in  bell  shaped  magnets  (Fig.  Ill)  placed 
horizontally  and  in  the  same  axis  with  the  armature,  instead  of 
the  customary  horse-shoe  magnets  placed  at  right  angle  to  the 
armature. 

This  at  once  makes  possible  and  practicable  the  simultaneous 
advance  and  retard  of  magnets  and  breaker  instead  of  the  ad- 
vance and  retard  of  the  breaker  alone  as  the  magnets  may  be 
moved  to  and  fro  with  the  breaker  housing.  It  will  be  seen  that 
as  a  result  of  this  new  departure  the  relative  position  of  arma- 
ture and  field  at  the  moment  of  sparking  is  absolutely  main- 
tained, and  the  same  quality  of  spark  is  therefore  produced,  no 
matter  what  the  timing  may  be.  Furthermore,  the  range  of 
timing,  which  with  the  horse-shoe  type  of  magneto  is  limited 
to  10°  or  15°  at  low  speeds  (i.  e.  at  speeds  at  which  a  retarded 
spark  is  of  value)  becomes  limited  only  by  the  necessity  of 
supplying  a  suitable  support  for  the  magnets.  With  the  stand- 
ard types  of  Mea  magnetos  described  in  the  following,  this 
range  varies  from  about  45°  to  70°,  but  if  necessary  this  range 
can  be  increased  to  any  amount  desired. 

The  bell-shaped  magnets  are  fixed  to  the  casing  which  is 
mounted  on  a  base  supplied  with  the  magneto.  The  timing  is 
altered  by  turning  the  casing  and  magnets  together  on  the  base. 

Fig.  112  shows  a  longitudinal  section  of  a  four  cylinder  Mea 
magneto.  The  armature  F  with  the  ball  bearings  17-18  rotates 
in  the  bell-shaped  magnets  100,  the  poles  of  the  magnets  being 
on  a  horizontal  line  opposite  the  armature  1.  The  armature  is  of 
the  ordinary  H  type  iron  core  wound  with  a  double  winding  of 
heavy  primary  and  fine  secondary  wire.  On  the  armature  are 
mounted  the  condenser  12,  the  high  tension  collector  ring  4, 
and  the  low  tension  circuit  breaker  26-39. 

The  circuit  breaker  consists  of  a  disc  27  on  which  are  mounted 
the  short  platinum  33,  the  other  contact  point  34  is  movable 
and  is  supported  by  a  spring  30  which  is  fastened  to  the  in- 
sulated plate  28  mounted  on  disc  27.  Fiber  roller  31  in  con- 
nection with  cam  disc  40  which  is  provided  with  two  cams  is 
located  inside  the  breaker.  Revolving  with  the  armature  the 
roller. presses  against  the  spring  supported  part  of  the  breaker 
whenever  it  rolls  over  the  two  cams  which  of  course  is  twice 
per  revolution. 

Inspection  of  the  breaker  points  is  made  easy  by  an  opening 
in  the  side  of  the  breaker  box.  The  box  is  closed  by  a  cover 
74  supporting  at  its  centre  the  carbon  holder  47  by  means  of 


GAS,  OIL  AND  STEAM  ENGINES 


263 


which  the  carbon  46  is  pressed  against  screw  24.  This  latter 
screw  connects  with  one  end  of  the  low  tension  winding  while 
the  other  end  is  connected  to  the  core  of  the  armature.  It 


Magneto   of  Roberts   Motor  in  Advanced   Position. 

will,  therefore,  be  seen  that  the  breaker  ordinarily  short-circuits 
the  low  tension  winding  and  that  this  short-circuit  is  bioken 
only  when  the  breaker  opens;  it  will  also  be  apparent  that  when 


112-a.  Advance  and  Retard  Mechanism  Used  in  the  Roberts  Motors. 
The  Magneto  is  Driven  by  a  Helical  Gear  from  the  Small  Pinion. 
By  Shifting  the  Gfcar  Back  and  Forth  on  the  Pinion,  the  Armature 
of  the  Magneto  is  Advanced  or  Retarded  in  Regard  to  the  Piston 
Position.  The  Reason  for  this  Change  Will  be  Seen  from  the 
Cuts  by  Noting  the  Position  of  the  Lower  Helix. 

the  screw  24  is  grounded  through  terminal  50  and  the  low-ten- 
sion switch  to  which  it  is  connected,  the  low-tension  winding 


264  GAS,  OIL  AND  STEAM  ENGINES 

remains  permanently  short-circuited,  so  that  the  magneto  will 
not  spark.  The  entire  breaker  can  be  removed  by  loosening 
screw  24. 

The  high  tension  current  is  collected  from  collector  ring  4  by 
means  of  brush  77  and  brush  holder  76,  which  are  supported  by 
a  removable  cover  91  which  also  supports  the  low  tension 
grounding  brush  78  provided  to  relieve  the  ball  bearings  of  all 
current  which  might  be  injurious.  Cover  91  also  carries  the 
safety  gap  89  which  protects  the  armature  from  excessive  volt- 
ages in  case  the  magneto  becomes  disconnected  from  the  spark 
plugs. 

The  distributor  consists  of  the  stationary  part  70  and  the 
rotating  part  60  which  is  driven  from  the  armature  shaft  through 
steel  and  bronze  gears  7  and  72.  The  current  reaches  this  dis- 
tributor from  carbon  77  through  bridge  84  and  carbon  69.  It  is 
conducted  to  brushes  68  placed  at  right  angles  to  each  other 
and  making  contact  alternately  with  four  contact  plates  em- 
bedded in  part  70.  These  plates  are  connected  to  contact  holes 
in  the  top  of  the  distributor,  into  which  the  terminals  of  cables 
leading  to  the  different  cylinders  are  placed. 

In  the  front  plate  of  the  magneto  is  provided  a  small  window, 
behind  which  appear  numbers  engraved  on  the  distributor  gear 
which  correspond  to  the  number  of  the  cylinder  the  magneto  is 
firing.  This  indicator  is  of  great  value  as  it  allows  a  setting  or 
resetting  after  taking  out,  without  the  necessity  of  opening  up 
the  magneto  to  find  out  where  the  distributor  makes  contact. 

The  magneto  proper  is  mounted  in  the  base  53  which  is 
bolted  to  the  motor  frame  and  the  arrangement  is  such  that  the 
magneto  can  be  removed  from  its  base  by  removing  the  top 
parts  60a  and  60b  of  the  two  bearings.  The  variation  in  timing 
is  affected  by  turning  the  magneto  proper  in  the  stationary  base 
which  is  accomplished  by  the  spark  lever  connections  attached 
to  one  of  the  side  lugs  88.  The  spark  is  advanced  by  turning 
the  magneto  opposite  to  rotation  and  is  retarded  by  turning  it 
with  rotation.  One  cylinder  magnetos  are  similar  to  the  four 
cylinder  except  that  the  distributor  and  gears  are  omitted. 

(103)  The  Wico  High  Tension  Igniter. 

The  Wico  igniter  produces  a  spark  similar  tc  that  of  the 
conventional  high  tension  magneto  exce.pt  that  the  heat  of  the 
spark  is  independent  of  the  engine  speed.  In  other  respects  it 
is  very  different  from  the  types  described  in  the  preceding 
pages  for  its  motion  is  reciprocating  instead  of  being  rotary,  and 


GAS,  OIL  AND  STEAM  ENGINES 


265 


because  all  of  the  wire  is  stationary,  the  only  movement  being 
that  of  the  iron  core  that  passes  through  the  center  of  the 
fields.  The  fact  that  the  spark  is  of  the  same  intensity  at  all 
speeds  makes  this  device  particularly  desirable  in  starting  the 
engine  at  which  time  the  mixture  is  always  of  the  poorest 
quality. 
It  is  very  simple,  and  is  without  condensers,  contact  points 


Fig.    113.     Wico    Igniter.     High    Tension    Reciprocating    Type. 

or  primary  windings,  and  has  no  parts  that  require  adjustment. 
The  current  is  generated  by  the  reciprocating  movement  of 
two  soft  iron  armatures  shown  as  a  bar  across  the  bottom  of 
the  two  coils,  which  move  alternately  into  and  out  of  contact 
with  the  ends  of  the  soft  iron  cores.  The  movement  of  these 
armatures  in  the  upward  direction  is  produced  by  the  motion  of 
the  engine  and  the  speed  of  this  movement  is,  of  course,  pro- 


266  GAS,  OIL  AND  STEAM  ENGINES 

portional  to  the  speed  of  the  engine.  The  downward  move- 
ment, which  produces  the  spark,  is  caused  by  the  action  of  a 
spring,  is  much  more  rapid  than  the  upward  movement  and 
entirely  independent  of  the  speed  of  the  engine. 

The  magnets  are  made  of  tungsten  steel,  shown  as  two  bars 
across  the  top  of  the  coils,  hardened  and  magnetized  and  are 
fastened  by  machine  screws  to  the  cast  iron  pole  pieces,  which 
serve  to  carry  the  magnetic  lines  of  force  from  the  poles  of 
the  magnets  to  the  soft  iron  cores.  The  cores,  which  fit  into 
slots  milled  in  the  pole  pieces,  are  laminated  or  built  up  of 
thin  sheets  of  soft  iron,  each  sheet  being  a  continuous  piece, 
the  full  length  of  the  core.  Each  core,  extends  from  just  below 
the  top  armature,  down  through  the  pole  piece,  and  coil  to  just 
above  the  bottom  armature. 

Each  armature  consists  of  a  number  of  laminations  or  sheets 
of  soft  iron  mounted  on  a  spool  shaped  bushing,  which,  in  turn, 
is  loosely  fitted  onto  the  squared  end  of  the  armature  bar.  The 
armature  bar  is  supported  with  a  sliding  fit  in  a  box  shaped 
guide  which  is  fastened  in  the  case. 

On  the  outer  ends  of  the  armature  bar  are  spiral  springs  held 
in  place  by  cup  shaped  washers  and  retaining  pins,  the  combina- 
tion making  a  self-locking  fastening  similar  to  the  familiar 
valve  spring  fastening  used  almost  universally  on  gas  engines. 
These  springs  bear  against  the  armatures  and  tend  to  force 
them  against  the  shoulders  of  the  armature  bar. 

The  coils  each  have  a  simple  high  tension  winding  of  many 
turns,  thoroughly  insulated  and  protected  against  mechanical 
injury.  They  are  connected  together  in  series  by  means  of  a 
metal  strip,  thus  making  one  continuous  winding.  In  the  single 
cylinder  igniter,  one  end  of  the  winding  is  grounded  to  the  case 
of  the  igniter,  while  the  other  end  is  connected  to  the  heavily 
insulated  lead  wire.  This  lead  wire  passes  out  through  a  stuf- 
fing box,  packed  with  wicking  and  thoroughly  water  tight,  direct 
to  the  spark  plug  in  the  cylinder. 

In  the  two  cylinder  machine  no  ground  connection  is  used, 
but  both  ends  of  the  winding  are  connected  to  lead  wires  pass- 
ing out  of  the  case  to  the  spark  plugs. 

The  action  of  the  igniter  is  as  follows: — As  the  driving  bar, 
through  its  connection  with  the  engine,  is  moved  downward  to 
its  limit  of  travel,  carrying  the  latch  with  it,  the  shoulder  on 
the  side  of  the  latch  snaps  under  the  head  of  the  latch  block. 
As  the  motion  reverses  the  latch  carries  the  latch  block  and  ar- 
mature bar  upward.  The  lower  armature,  being  in  contact  with 


GAS,  OIL  AND  STEAM  ENGINES  267 

the  stationary  cores,  cannot  rise  with  the  armature  bar,  but  the 
lower  armature  spring  is  compressed  between  its  retaining 
washer  and  the  armature,  while  the  bar  rises  and  carries  with  it 
the  upper  armature,  which  bears  against  the  upper  shoulders 
on  the  bar. 

As  the  driving  bar  continues  its  upward  motion  the  upper  end 
of  the  latch  meets  the  lower  end  of  the  timing  wedge  and,  as 
the  wedge  is  held  stationary  by  the  timing  quadrant,  a  further 
movement  of  the  latch  causes  it  to  be  pushed  aside  until  the 
shoulder  on  the  latch  clears  the  latch  block  and  releases  it. 

As  the  lower  armature  spring  is  at  this  time  exerting  a  pres- 
sure between  the  armature  bar  and  cores  through  the  medium 
of  the  lower  armature,  the  instant  the  latch  block  is  released, 
the  armature  bar  is  quickly  pulled  downward,  carrying  the 
upper  armature  with  it.  Just  before  the  motion  of  the  upper 
armature  is  stopped  by  its  coming  in  contact  with  the  cores, 
the  lower  shoulders  on  the  armature  bar  come  in  contact  with 
the  lower  armature,  and,  as  the  bar  has  acquired  considerable 
velocity,  its  momentum  carries  the  lower  armature  away  from 
the  cores  against  the  pressure  of  the  upper  armature  spring, 
which  thus  acts  as  a  buffer  to  gradually  stop  the  movement 
of  the  armature  bar.  The  armature  bar  finally  settles  in  a 
central  position. 

The  timing  of  the  spark  is  accomplished  by  releasing  the  ar- 
mature bar  earlier  or  later  in  the  stroke.  This  is  done  by  shift- 
ing the  position  of  the  eccentric  timing  quadrant,  which  in  turn 
varies  the  position  of  the  wedge  so  that  the  latch  strikes  it 
earlier  or  later  in  the  stroke.  The  timing  quadrant  is  furnished 
with  several  notches  into  one  of  which  the  top  of  the  wedge 
rests,  thus  holding  the  quadrant  in  the  desired  position. 

The  motion  should  preferably  be  taken  from  an  eccentric  on 
the  cam  shaft  of  a  single  cylinder  four  cycle  engine,  or  the 
crank  shaft  of  a  single  cylinder  two  cycle  or  a  two  cylinder 
four  cycle  engine.  On  a  two  cylinder  four  cycle  engine,  it  is 
sometimes  more  convenient  to  drive  the  igniter  from  the  cam 
shaft,  using  a  two  throw  cam  to  produce  the  required  number 
of  sparks.  In  this  case  the  shape  of  the  cam  should  be  such  as 
to  duplicate  the  motion  of  the  eccentric.  That  is,  it  should  start 
the  driving  bar  slowly  from  its  lower  position,  move  it  most 
rapidly  at  mid  stroke  and  bring  it  to  rest  gradually  at  the  upper 
end  of  the  stroke,  exactly  as  is  done  by  the  eccentric  motion. 

When  an  eccentric  is  already  on  the  engine  the  motion  may 
be  taken  from  it  to  an  igniter  with  a  driving  bar  through  a 


268 


GAS,  OIL  AND  STEAM  ENGINES 


properly  proportioned  lever  that  will  give  the  required  length 
of  stroke.  Where  a  plunger  pump  is  used  on  the  engine  the 
motion  can  usually  be  taken  from  the  pump  rod.  Where"  an 
eccentric  has  to  be  provided  especially  for  the  igniter,  the  driv- 
ing bar  is  generally  used  with  its  roller  running  on  the  eccentric. 

(104)  Starting  On  Magneto  Spark. 

A  four-cylinder  engine  in  good  condition  will  come  to  rest 
with  the  pistons  approximately  midway  on  the  stroke  and  bal- 
anced between  the  compression  of  the  compressing  cylinder  and 
of  the  power  cylinder.  When  the  cylinders  of  such  an  engine  are 
charged  with  a  proper  mixture,  the  engine  will  start  by  the  igni- 


PLATINUM 
SCREW 


NTERRl/PTER 
SPR!MG 


PLATINUM    SCREW 


INTERRUPTER 

LEVER 


TIMING   CONTROL 
ARM 


STEEL  SEGMENT 


Fig.  114.     Bosch  Dual  System. 

tion  of  the  mixture  contained  in  the  compressing  cylinder,  for 
the  pressure  produced  by  the  ignited  gas  will  be  sufficient  to 
rotate  the  crankshaft. 

It  is  essential,  for  the  ignition  system  to  be  so  arranged  that 
a  spark  can  be  produced  at  any  point  in  the  piston  travel,  and 
in  this  the  Bosch  dual,  duplex  and  two  independent  systems  are 
successful. 

The  Bosch  dual  system,  Fig.  114,  is  part  of  the  equipment  of 
many  of  the  cars  and  engines  marketed,  and  is  composed  of 
two  separate  and  distinct  ignition  systems,  one  supplying  igni- 
tion by  direct  high-tension  magneto,  and  the  other  by  a  battery 
and  high-tension  coil.  These  two  systems  consist  in  reality  of 
but  two  main  parts;  the  dual  magneto,  incorporating  a  separate 
battery  timer,  and  the  single  unit  dual  coil  with  its  battery. 
The  sparking  current  from  either  battery  or  magneto  is  brought 


GAS,  OIL  AND  STEAM  ENGINES 


269 


to  the  magneto  distributor,  so  that  the  only  parts  used  in  com- 
mon are  the  distributor  and  the  spark  plugs;  the  common  use 
of  the  latter  for  both  magneto  and  battery  systems  is  cause  for 
the  popularity  of  the  dual  system  for  motors  having  provision 
for  only  one  set  of  plugs. 

In  both  the  magneto  and  the  battery  sides  the  spark  is  pro- 
duced on  the  breaking  of  the  circuit,  and  the  coil  is  so  arranged 
that  by  pressing  a  button  when  the  switch  is  in  the  battery 
position,  an  intense  vibrator  spark  is  produced  in  the  cylinder 
during  that  period  when  the  circuit  breaker  is  open,  which  will 
be  the  case  during  the  first  three-fourths  of  the  power  stroke. 
The  current  is  transmitted  to  the  distributor  and  passes  through 
the  spark  plug  of  the  cylinder  that  is  on  the  power  stroke. 


BATTERY  TIMER 


INTERRUPTER 
"ADJUSTMENT 

SHORT 
^-CIRCUITING 
TERMINAL 


8ATTERY  \  j 

CONNECTION        \\ 


\. 


PLATINUM     POINTS 


Fig.   115.      Bosch  Duplex  Breaker. 

Should  the  engine  come  to  a  stop  in  such  a  position  that  the 
battery  timer  is  closed,  it  will  not  be  possible  to  produce  a 
vibrator  spark  by  the  pressing  of  the  button,  but  the  releasing 
of  the  button  will  produce  a  single  contact  spark  that  will  ignite 
the  mixture  and  thus  start  the  engine. 

Thus  if  the  engine  should  stop  in  some  odd  position,  and 
the  spark  is  produced  when  the  piston  is  slightly  before  top 
center,  for  instance,  there  will  be  a  slight  reverse  impulse  which 
will  bring  another  cylinder  on  the  power  stroke  and  into  the 
ignition  circuit.  The  engine  will  thereupon  take  up  its  cycle 
in  the  proper  direction. 

In  the  Bosch  duplex  system  the  coil  is  in  series  with  the 
magneto  armature,  but  the  spark  is  produced  under  the  same 
condition,  that  is,  on  the  breaking  of  the  circuit.  In  conse- 
quence the  Bosch  duplex  system  will  permit  the  production 


270 


GAS,  OIL  AND  STEAM  ENGINES 


of  a  spark  during  the  first  three-quarters -of  the  power  stroke 
by  the  pressing  of  the  push  button  set. on  the  switch  plate. 

The  Bosch  two  independent  system  is  composed  of  a  separate 
Bosch  battery  system  and  a  separate  Bosch  magneto.  Although 
the  operation  of  the  coil  is  somewhat  similar  to  that  of  the 


The  Herz  High  Tension  Magneto  in  Which  the  Magnets  are  Built  up  of  Thin 
Steel   Plates   Without   Pole   Pieces    (Four    Cylinder   Type). 

dual  system,  the  nature  of  the  battery  system  is  such  as  to  re- 
quire arrangements  for  two  separate  sets  of  spark  plugs.  The 
coil  is  not  unlike  that  supplied  with  the  dual  system  in  that  by 
pressing  a  button  located  on  the  switch  plate  a  series  of  in- 
tense sparks  may  be  produced  in  the  cylinder  at  all  advanta- 
geous points  of  the  power  stroke. 


CHAPTER  IX 
CARBURETORS 

(105)  Principles  of  Carburetion. 

The  carburetor  is  a  device  for  converting  volatile  liquid  fuels, 
such  as  gasoline,  alcohol,  kerosene,  etc.,  into  an  explosive  vapor. 
Besides  vaporizing  the  liquid,  the  carburetor  also  controls  the 
proportion  of  the  fuel  to  the  air  required  for  its  combustion. 
The  mixture  produced  by  the  carburetor  must  be  a  uniform  gas 
and  not  a  simple  spray  to  accomplish  the  best  results  for  com- 
plete and  instantaneous  combustion.  Proper  combustion  can- 
not be  attained  with  any  of  the  fuel  in  a  liquid  state  as  all 
of  the  fuel  contained  in  a  liquid  particle  cannot  come  into  con- 
tact with  the  consuming  air.  It  is  of  the  utmost  importance 
to  have  the  air  and  fuel  in  correct  proportions  so  that  the  fuel 
may  be  completely  consumed  without  danger  of  interfering 
with  the  ignition  by  an  excess  of  air. 

With  few  exceptions  modern  gasoline  carburetors  are 
of  the  nozzle  type  in  which  the  liquid  is  broken  up  into  an 
extremely  fine  subdivided  state  by  the  suction  of  the  engine 
piston.  This  fine  spray  is  then  fully  vaporized  or  gasified  by 
the  heat  drawn  from  the  surrounding  intake  air  that  is  drawn 
through  the  carburetor  and  into  the  cylinder  on  the  suction 
stroke.  Owing  to  the  low  grade  fuels  now  on  the  market  and 
to  the  constantly  varying  atmospheric  conditions  it  is  seldom 
possible  to  obtain  a  perfect  vapor  in  the  correct  proportions, 
and  for  this  reason  much  heat  is  lost  that  would  be  available 
were  the  mixture  perfect. 

Carburetors  for  automobiles  and  boats  vary  in  detail  from 
those  used  on  stationary  engines  due  principally  to  the  differ- 
ence in  matters  of  speed.  A  stationary  engine  runs  at  a  con- 
stant speed  which  makes  adjustment  comparatively  easy,  while 
automobile  engines  have  a  wide  range  of  speeds  and  loads  mak- 
ing it  very  difficult  to  maintain  the  correct  mixture  at  all  points 
in  the  range.  The  difference  in  the  fuel  and  air  adjustments 
for  varying  of  speeds  marks  the  principal  difference  between 
stationary  and  automobile  carburetors.  There  are  many  types 

271 


272 


GAS,  OIL  AND  STEAM  ENGINES 


of  successful  carburetors  on  the  market,  so  many  in  fact  that  we 
have  room  for  the  description  of  only  three  or  four  of  the 
most  prominent,  but  we  will  say  that  the  well  known  car- 
buretors are  based  on  the  same  principles  and  differ  only  in 
matters  of  detail. 

A  cross-sectional  view  of  the  well  known  Schebler  Type  D 
carburetor  is  shown  by  Fig.  116,  and  is  of  the  type  commonly 
used  on  automobile  motors  and  boats. 

(106)  Schebler  Carburetor. 

The  carburetor  is  connected  to  the  intake  of  the  engine  by 

MODEL  "D" 


Fig.    116.     Cross-Section    Through    Type    "D"    Schebler    Carburetor. 

pipe  screwed  into  the  opening  R,  the  gas  passing  from  the  car- 
buretor to  the  engine  through  this  opening. 

D  is  the  spray  nozzle  which  opens  into  the  float  chamber  B, 
the  opening  of  the  nozzle  being  regulated  by  needle  valve  E 
which  controls  the  quantity  of  gasoline  flowing  into  the  mixing 
chamber  C. 

On  the  suction  stroke  of  the  engine,  air  is  drawn  through  the 
upper  left  hand  opening,  past  the  partially  open  auxiliary  air 


GAS,  OIL  AND  STEAM  ENGINES  273 

valve  A,  past  the  needle  valve  D,  through  the  mixing  chamber 
C,  and  into  the  engine  through  R. 

The  suction  of  the  engine  produces  a  partial  vacuum  in  the 
mixing  chamber  C  which  causes  the  gasoline  to  issue  from  the 
nozzle  D,  in  the  form  of  a  fine  spray  which  ^is  taken  up  by  the 
air  passing  through  the  passage  H,  and  is  taken  into  the  engine 
through  R,  thoroughly  mixed.  The  amount  of  mixture  entering 
the  engine,  and  consequently  the  engine  speed  is  regulated  by 
the  throttle  valve  K,  operated  by  the  lever  P. 

In  order  that  the  amount  of  spray  given  by  the  nozzle  P  be 
constant  it  is  necessary  that  the  level,  or  height  of  the  gasoline 
in  the  nozzle  be  constant.  The  level  is  maintained  by  means 
of  the  float  F,  which  opens,  or  closes  the  gasoline  supply  valve 
H,  opening  it  and  allowing  gasoline  to  enter  when  the  level  is 
low,  and  closing  the  valve  when  the  level  is  high. 

The  carburetor  is  connected  to  the  gasoline  supply  tank,  by 
pipe  connected  to  the  inlet  G,  through  which  the  gasoline  flows 
into  the  float  chamber  B.  The  float  chamber  carries  a  small 
amount  of  gasoline  on  which  the  float  F  rests.  The  richness 
of  the  mixture  is  controlled  by  opening  or  closing  the  nozzle 
needle  valve  E,  which  passes  through  the  center  of  the  nozzle  D. 

The  float  F  surrounds  the  nozzle  in  order  to  keep  the  level  of 
the  liquid  constant  when  the  carburetor  is  tilted  out  of  the 
horizontal  by^  climbing  hills,  or  by  the  rocking  of  the  boat 
when  used  on  a  marine  engine. 

A  drain  cock  T  is  placed  at  the  bottom  of  the  float  chamber 
for  the  purpose  of  removing  any  water,  or  sediment  that  may 
collect  in  the  bottom  of  the  float  chamber. 

At  low  speeds,  the  auxiliary  air  valve  A  lies  tight  on  its  seat, 
allowing  a  constant  opening  for  the  incoming  air  through  the 
space  shown  at  the  bottom  of  the  valve. 

When  the  speed  of  the  engine  is  much  increased,  the  vacuum 
is  increased  in  the  mixing  chamber  C,  which  overcomes  the 
tension  of  the  air  valve  spring  O  and  allows  the  valve  to  open 
and  admit  more  air  to  the  mixing  chamber.  The  action  of  the 
auxiliary  air  valve  keeps  the  mixture  uniform  at  different  en- 
gine speeds,  as  it  tends  to  keep  the  vacuum  constant  in  the  mix- 
ing chamber. 

When  the  engine  speed  increases,  the  flow  of  gasoline  is 
greater,  and  consequently  more  air  will  be  required  to  burn  it; 
this  additional  air  is  furnished  by  the  automatic  action  of  the 
valve,  and  when  once  adjusted,  compensates  accurately  for  the 
different  engine  speeds. 


274  GAS,  OIL  AND  STEAM  ENGINES 

The  gasoline  is  generally  supplied  by  a  tank  elevated  at  least 
six  inches  above  the  level  of  the  fluid  in  the  float  chamber;  al- 
though in  some  cases  the  gasoline  is  supplied  by  air  pressure  on 
a  tank  situated  below  the  level  of  the  carburetor. 

In  some  types  of  Schebler  carburetors,  the  float  chamber  B 
is  surrounded  by  a  water  jacket  that  is  supplied  with  hot  water 
from  the  cylinder  jackets  of  the  engine.  This  keeps  the  gasoline 
warm  so  that  it  evaporates  readily  under  any  atmospheric  con- 
ditions. 

The  quantity  of  air  admitted  to  the  carburetor  is  controlled 
by  an  air  valve  shown  in  the  air  intake  by  the  dotted  lines. 
This  is  adjusted  by  hand  for  a  particular  engine  and  is  seldom 
touched  afterward. 

When  starting  the  engine  it  is  necessary  to  have  a  very  rich 
mixture  for  the  first  few  revolutions,  this  mixture  being  ob- 
tained by  "flooding"  the  carburetor. 

On  the  Schebler  carburetor  the  mixing  chamber  is  flooded  by 
depressing  the  "tickler"  or  flushing  pin  V. 

(107)  Two  Cycle  Carburetors. 

Nearly  any  type  of  carburetor  can  be  used  on  a  two  port,  two 
stroke,  cycle  engine  providing  a  check  valve  is  placed  between 
the  crank  case  and  carburetor  to  prevent  the  crank-case  com- 
pression from  forcing  its  contents  back  through  the  inlet  pas- 
sages. A  great  many  manufacturers  make  special  carburetors 
for  two  stroke  motors  that  have  the  check  valve  built  into  the 
carburetor  itself.  With  three  port  two  stroke  cycle  engines  a 
check  valve  is  not  necessary  as  the  piston  in  this  type  of  engine 
performs  this  duty. 

In  that  class  of  vaporizers  known  as  mixing  valves,  the  valve 
that  controls  the  flow  of  gasoline  blocks  the  air  passage  in  such 
a  way  that  an  additional  check  valve  is  not  necessary. 

(108)  Kingston  Carburetors. 

The  Kingston  Carburetor  shown  by  Fig.  117  differs  from  the 
Schebler  in  many  details,  the  principal  difference  being  in  the 
construction  of  the  spray  nozzle  and  the  construction  of  the 
auxiliary  air  valve.  The  throttle  valve  E  controlls  the  exit  of 
the  mixture  through  the  engine  connection  C  which  is  an  ex- 
tension of  the  mixing  chamber.  The  spray  nozzle  J  which  is 
surrounded  by  a  hood  or  tube  is  controlled  by  the  needle  valve 
A  which  is  threaded  into  the  top  of  the  mixing  chamber,  this 


GAS,  OIL  AND  STEAM  ENGINES  275 

latter   adjustment   being  locked   into  place  by  a  button   head 
screw  and  a  slot  in  the  casting. 

Surrounding  the  nozzle  tube  or  hood  is  a  curved  restriction 
in  the  air  intake  passage,  is  known  as  a  Venturi  tube,  which 
insures  a  constant  relation  between  the  air  and  fuel  supplies. 
As  the  action  of  the  Venturi  tube  is  rather  complicated,  it  will 
not  be  taken  up  in  detail.  Air  is  supplied  to  the  Venturi 
passage  through  the  intake  (D).  An  annular  float  (K)  sur- 
rounds the  mixing  chamber  that  acts  on  the  gasoline  sup- 
ply valve  (I)  through  a  short  lever  arm.  This  valve  is  acces- 
sible for  cleaning  on  the  removal  of  the  cap  H  that  covers  the 


Fig.     117.     Cross-Section    Through     Kingston     Carburetor     Showing    Balls 
Used    for   Auxiliary   Air  Valves. 

valve  chamber.  Gasoline  enters  the  float  chamber  through 
the  fuel  pipe  G,  and  enters  the  spray  nozzle  through  the  two 
ports  in  the  base  of  the  mixing  chamber. 

The  auxiliary  air  valve  is  a  particularly  novel  feature  of  this 
carburetor,  as  no  springs  nor  disc  valves  are  used  in  its  con- 
struction. Five  balls  (M)  of  different  weights  and  sizes  act 
as  air  valves,  the  balls  covering  the  inlet  ports  (L)  under  nor- 
mal operation.  As  the  speed  increases,  the  balls  are  lifted  off 
their  seats  in  order  of  their  weight  or  size  by  the  increase  in 


276  GAS,  OIL  AND  STEAM  ENGINES 

suction.  With  a  slight  increase  of  suction,  the  lightest  ball  cov- 
ering the  smallest  hole  is  lifted  first,  a  further  increase  in  suc- 
tion lifts  the  next  largest  ball  which  still  further  increases  the 
auxiliary  air  intake,  and  so  on  until  at  the  highest  speed  all 
of  the  balls  are  off  their  seats.  Access  ID  the  ball  valves  is  had 
through  the  valve  caps  (N).  The  constant  supply  inlet  is 
circular  and  may  be  set  at  any  desired  angle,  as  can  the  float 
chamber  and  gasoline  supply  connection.  Control  and  adjust- 
ment are  entirely  by  the  needle  valve. 


(109)  The  Feps  Carburetor. 

The  Feps  carburetor  has  the  main  needle  valve  surrounded 
by  a  Venturi  chamber  as  in  the  preceding  case,  the  needle  valve 
adjustment  being  made  through  a  lever  on  the  left  of  the  mix- 
ing chamber.  An  auxiliary  nozzle  directly  under  the  auxiliary 
air  valve  at  the  right,  connects  with  the  float  chamber  and 
furnishes  an  additional  mixture  of  gasoline  and  air  for  hill 
climbing  and  high  speed  work  when  the  leather  faced  auxiliary 
air  valve  lifts  from  its  seat.  The  adjustment  for  this  auxiliary 
jet  is  shown  at  the  right  of  the  air  valve  chamber. 

For  intermediate  speeds,  the  air  valve  alone  is  in  action.  No 
controlling  springs  are  used  on  the  air  valve  which  insures  posi- 
tive action  and  sensitive  control  of  the  air.  A  float  surrounding 
the  Venturi  tube  controls  the  fuel  valve  through  the  usual  lever 
arm.  A  wire  gauze  strainer  placed  in  the  fuel  chamber  to  the 
left  prevents  dirt  and  water  from  being  drawn  into  the  nozzle, 
and  as  this  strainer  easily  removed  it  is  a  simple  matter  to  clean 
and  prevent  the  troubles  due  to  dirty  fuel. 

By  closing  the  upper  valve  in  the  vertical  engine  connection 
the  vacuum  is  increased  in  the  manifold  when  starting  the  en- 
gine. This  increase  of  vacuum  draws  gasoline  from  the  float 
chamber  and  primes  the  engine  making  the  engine  easy  to  start 
in  cold  weather.  The  tube  through  which  the  gasoline  is  drawn 
for  priming  is  the  small  crooked  tube  bending  over  the  float  and 
terminating  above  the  starting  valve.  Below  this  valve  is  the 
throttle  valve  which  controls  the  mixture  in  the  ordinary  man- 
ner. The  adjustment  for  intermediate  speeds  is  made  by  the 
center  knurled  thumb-screw  shown  over  the  air  valve  chamber 
which  controls  the  travel  of  auxiliary  air  valve.  In  effect  this  is 
a  double  carburetor,  one  jet  for  high  speed  and  one  for  low. 


GAS,  OIL  AND  STEAM  ENGINES 


277 


(111)  Gasoline  Strainers. 

Much  trouble  is  caused  in  carburetors  by  dirt,  water  and 
sediment,  collecting  in  the  small  passages  and  obstructing  the 
flow  of  the  gasoline. 

The  purpose  of  the  gasoline  strainer  is  to  prevent  any  water 


Fig.  119.  The  Excelsior  Carburetor  in  Which  the  Air  is  Regulated  by  a  Ball 
which  Lies  in  the  Tapering  Venturi  Tube.  An  Increase  of  Suction 
Lifts  the  Ball  and  Allows  More  Air  to  Pass. 

or  foreign  matter  from  being  carried  into  the  carburetor,  and 
this  device  should  be  used  on  every  engine  if  the  owner  wishes 
to  be  free  from  carburetor  troubles. 

(112)  Installing  Gasoline  Carburetors. 

(1)  Use  brass  or  copper  pipe  from  the  tank  to  carburetor  if 
possible  to  avoid  trouble  from  dirt  and  flakes  of  rust. 

(2)  When  installing  a  gasoline  tank  be  sure  that  the  bottom 
of  the  tank  is  at  least  six  inches  above  the  carburetor  to  insure 
a  good  flow. 


278  GAS,  OIL  AND  STEAM  ENGINES 

(3)  The  tank  should  be  provided  with  an  air  vent  hole,  or 
the  gasoline  will  not  flow  because  of  the  vacuum  in  the  top  of 
the  tank* 

(4)  All  tanks  should  be  provided  with  a  drain  cock  at  the 
lowest  point  so  that  water  and  dirt  may  be  easily  removed. 

(5)  Clean  out  the  tank  thoroughly  before  rilling  with  gaso- 
line to  avoid  clogged  carburetors. 

(6)  Pipes  from  the  tank  to  carburetor  should  never  be  placed 
near  exhaust  pipes  or  hot  surfaces  for  the  gasoline  vapor  may 
prevent  the  feeding  of  gasoline. 

(7)  Clean  out  pipes  before  using. 

(8)  If  common  threaded  pipe  joints  are  used  on  the  gasoline 
piping,  use  common  soap  in  place  of  red  lead. 

(113)  Installing  the  Carburetor. 

The  carburetor  should  be  placed  as  near  to  the  cylinder  as 
possible,  the  shorter  the  pipe,  the  less  the  amount  of  vapor 
condensed  in  the  manifold.  With  multi-cylinder  engines  the 
carburetor  should  be  so  situated,  that  is,  an  equal  distance  from 
each  cylinder,  so  that  each  cylinder  will  inhale  an  equal  amount 
of  vapor. 

The  intake  opening  of  the  pipe  should  be  placed  near  one  of 
the  cylinders,  or  draw  warm  air  off  the  surface  of  the  exhaust 
pipe  in  order  that  gasoline  will  evaporate  readily  in  cold  weather, 
and  form  a  uniform  mixture  at  varying  temperatures. 

Great  care  should  be  taken  to  prevent  any  air  leaks  in  the 
carburetor,  or  intake  manifold  connections,  as  a  small  leak  will 
greatly  reduce  the  strength  of  the  mixture  and  cause  irregular 
running.  Always  use  a  gasket  between  the  valves  of  a  flanged 
connection  and  keep  the  bolts  tight.  If  a  brazed  sheet  brass 
manifold  is  used,  look  out  for  cracks  in  the  brazing. 

Leaks  may  be  detected  in  the  connections  by  spurting  a  little 
water  on  the  joints,  and  turning  the  engine  over  on  the  suction 
stroke.  If  the  water  is  sucked  in  the  leaks  should  be  repaired 
at  once.  Make  sure  when  placing  gaskets,  that  the  gasket  does 
not  obstruct  the  opening  in  the  pipe,  and  that  it  is  securely 
fastened  so  that  it  is  not  drawn  in  by  the  suction. 

Never  allow  the  carburetor  to  support  any  weight,  as  the  shell 
is  easily  sprung  which  will  result  in  leaking  needle  valves. 

CARBURETOR  ADJUSTMENT.  When  adjusting  the  car- 
buretor of  multiple  cylinder  engine,  it  is  advisable  to  open 
the  muffler  cutout  in  order  that  the  character  of  the  exhaust 
may  be  seen  or  heard.  With  the  muffler  open,  the  color  of 


GAS,  OIL  AND  STEAM  ENGINES  279 

the  exhaust  should  be  noted.  With  a  PURPLE  flame  you  may 
be  sure  that  the  adjustment  is  nearly  correct  for  that  load 
and  speed;  a  yellow  flame  indicates  too  much  air;  a  thin  blue 
flame  too  much  gasoline,  and  is  not  the  best  for  power. 

Before  starting  for  the  adjustment  test,  try  the  compression, 
and  the  spark.  If  the  compression  is  poor,  try  the  effects  of  a 
little  oil  on  the  piston,  which  may  be  introduced  into  the  cyl- 
inder through  the  priming  cup.  It  will  be  well  to  dilute  the  oil 
to  about  one-half  with  kerosene.  After  all  trouble  with  all  the 
parts  are  clear,  you  may  start  the  engine. 

Turn  on  the  gasoline  at  the  tank,  and  after  standing  a  moment 
see  whether  there  is  any  dripping  at  the  carburetor,  if  there  is, 
the  trouble  will  probably  be  due  to  a  leaky  float,  dirt  in  the 
float  valve,  or  to  poor  float  adjustment.  Locate  the  leak  and 
remedy  it  before  proceeding  further.  Dirt  on  the  seat  of  the 
needle  valve  may  sometimes  be  removed  by  "flooding"  the  car- 
buretor, which  is  done  by  holding  down  the  "tickler"  lever  for 
a  few  seconds,  causing  the  gasoline  to  overflow,  and  wash  out 
the  dirt. 

If  the  motor  has  been  standing  for  a  time  it  would  be  well  to 
"prime"  the  motor  by  admitting  a  little  gasoline  into  the  cyl- 
inder through  the  priming  cup,  or  by  pushing  the  tickler  a 
couple  of  times  so  as  to  slightly  flood  the  carburetor. 

Now  turn  on  the  spark  and  turn  over  the  engine  for  the  start, 
taking  care  that  the  throttle  is  just  a  little  farther  open  than  its 
fully  closed  position.  If  the  engine  takes  a  few  explosions  and 
stops,  you  will  find  the  nozzle,  or  that  some  part  of  the  fuel  pip- 
ing is  clogged  which  will  stop  the  engine.  If  the  motor  grad- 
usually  slows  down,  and  stops,  with  BLACK  SMOKE  issuing 
from  the  end  of  the  exhaust  pipe,  or  MISFIRES  badly,  the  mix- 
ture is  TOO  RICH,  and  should  be  reduced  by  cutting  down  the 
gasoline  supply  by  means  of  the  needle  valve  adjusting  screw. 
If  it  stops  quickly,  with  a  BACKFIRE,  or  explosion  at  the 
supply  of  gasoline  should  be  INCREASED  by  adjusting  the 
mouth  of  the  carburetor,  the  mixture  is  TOO  LEAN,  and  the 
needle  vaW, 

In  all  cases  be  sure  that  the  auxiliary  valves  are  closed  when 
the  engine  is  running  slowly,  with  the  throttle  closed,  as  in  the 
above  test.  If  they  are  open  at  low  speed,  the  mixture  will  be 
weakened  and  the  test  will  be  of  no  avail. 

After  adjusting  the  needle  valve  as  above  until  the  engine  is 
running  (with  throttle  in  the  same  partially  closed  position), 
turn  the  valve  slowly  in  one  direction  or  the  other  until  the 


280  GAS,  OIL  AND  STEAM  ENGINES 

motor  seems  to  be  running  at  its  best.  During  the  above  tests 
the  spark  should  be  left  retarded  throughout  the  adjustment, 
and  the  throttle  should  not  be  moved. 

The  carburetor  should  now  be  tested  for  high  speed  adjust- 
ment, by  opening  the  throttle  wide  (spark  l/4  advanced),  and 
observing  the  action  of  the  motor.  If  the  engine  back-fires 
through  the  carburetor  at  high  speed,  it  indicates  that  the  mix- 
ture is  too  weak  which  may  be  due  to  the  auxiliary  air  valve 
spring  tension  being  too  weak  and  allowing  an  excess  of  air  to 
be  admitted.  Increase  the  tension  of  the  spring,  and  if  this  does 
not  remedy  matters,  admit  a  little  more  fuel  to  strengthen  the 
mixture  by  means  of  the  needle  valve  adjustment.  Do  not  touch 
the  needle  valve  if  you  can  possibly  avoid  it,  or  the  high-speed 
adjustment,  as  the  fuel  adjustment  will  be  disturbed  for  low 
speed. 

If  the  engine  misfires,  with  loud  reports  at  the  exhaust,  does 
not  run  smoothly,  or  emits  clouds  of  black  smoke  at  high  speed, 
the  engine  is  not  receiving  enough  air  in  the  auxiliary  air  valve, 
consequently  the  tension  of  the  spring  should  be  reduced. 

Back  firing  through  the  carburetor  denotes  a  weak  mixture. 

Trouble  in  cold  weather  may  be  caused  either  by  slow  evapo- 
ration of  the  gasoline,  or  by  water  in  the  fuel  that  freezes  and  ob- 
structs the  piping  or  nozzle.  In  cold  weather  a  higher  gravity 
of  gasoline  should  be  used  than  in  summer,  as  it  evaporates 
more  readily,  and  therefore  forms  a  combustible  gas  the  rate 
at  lower  temperatures. 

To  increase  the  rate  of  evaporation  of  the  gasoline,  it  should 
be  placed  in  a  bottle  and  held  in  hot  water  for  a  time  before 
pouring  it  into  the  carburetor  or  tank,  or  the  air  inlet  warmed 
with  a  torch. 

The  cylinder  water  jacket  should  always  be  filled  with  hot 
water  before  trying  to  start  the  engine,  and  will  prevent  the  gas 
from  condensing  on  the  cold  walls  of  the  cylinder.  Often  good 
results  may  be  had  by  wrapping  a  cloth  or  towel  around  the 
carburetor,  that  has  been  dipped  in  hot  water. 

The  cylinder  of  an  air-cooled  engine  may  be  warmed  by  gently 
applying  the  heat  of  a  torch  to  the  ribs,  or  by  wrapping  hot 
cloths  about  it. 

The  tank,  piping,  and  carburetor  should  be  drained  more 
frequently  in  cold  weather  than  in  hot,  to  prevent  any  accumu- 
lation of  water  from  freezing,  and  stopping  the  fuel  supply.  A 
gasoline  strainer  should  always  be  supplied  on  the  fuel  line,  and 
should  be  regularly  drained. 

The  motor  may  often  be  made  to  start  in  cold  weather  by 


GAS,  OIL  AND  STEAM  ENGINES  281 

cutting  out  the  spark,  and  cranking  the  engine  two  or  three 
revolutions  with  the  throttle  wide  open.  The  throttle  should 
now  be  closed  within  J/£  of  its  fully  closed  position,  the  ignition 
current  turned  on,  and  the  engine  cranked  for  starting.  This 
system  will  very  seldom  fail  of  success  at  the  first  attempt. 

Carburetor  flooding  is  shown  by  the  dripping  of  gasoline 
from  the  carburetor,  and  which  results  in  too  much  gasoline  in 
the  mixture.  Flooding  may  be  caused  by  dirt  accumulating 
under  float  valve,  by  a  leaking  float  (Copper  Float),  by  Water 
Logged  Float  (Shellac  worn  off  Cork  Float),  by  float  adjust- 
ment causing  too  high  a  level  of  gasoline,  by  leaking  float  valve, 
by  cutting  out  ignition  when  engine  is  running  full  speed,  by 
rust  or  corrosion  sticking  float  valve  lever,  by  float  binding  in 
chamber,  by  float  being  out  of  the  horizontal,  by  float  valve 
binding  in  guide,  by  excessive  pressure  on  gasoline,  or  by  tickler 
lever  held  against  float  continuously. 

Dirt  accumulated  under  float  valve  may  sometimes  be  flushed 
out  by  depressing  tickler  lever  several  times;  if  this  does  not 
suffice,  the  cap  over  the  valve  must  be  removed,  and  the  orifice 
cleaned  by  wiping  with  a  cloth. 

LEAKING  FLOAT  VALVES  should  be  reground  with 
ground  glass  or  very  fine  sand;  never  use  emery  as  the  par- 
ticles will  become  imbedded  in  the  metal,  which  will  be  the 
cause  of  worse  leaks. 

Should  the  shellac  be  worn  off  of  a  cork  float  allowing  the 
gasoline  to  penetrate  the  pores  of  the  cork,  a  new  float  should 
be  installed,  as  it  is  a  doubtful  policy  for  owner  to  give  the 
float  an  additional  coat  of  shellac. 

MISFIRING  AT  LOW  SPEED.  If  the  carburetor  cannot 
be  adjusted  to  run  evenly  on  low  speed  after  making  all  pos- 
sible adjustments  with  the  needle  valve,  the  trouble  is  prob- 
ably due  to  air  leaks  between  the  carburetor  and  engine,  caused 
by  broken  gaskets,  cracked  brazing  in  the  intake  manifold,  or 
by  leaks  around  the  valve  stem  diluting  the  mixture. 

INCORRECT  VALVE  TIMING  will  cau*e  missing,  espe- 
cially on  multiple  cylinder  engines,  as  the  carburetor  cannot 
furnish  mixture  to  several  cylinders  that  have  different  indi- 
vidual timing.  Look  for  air  leaks  around  the  spark  edge  open- 
ings, and  be  sure  that  all  valves  seat  gas  tight.  Always  be 
sure  that  the  auxiliary  air  valve  remains  closed  at  low  speeds, 
as  a  valve  that  opens  at  too  low  a  speed  will  surely  cause  mis- 
firing as  it  dilutes  the  mixture. 

MISSING  in  one  cylinder  may  be  caused  by  an  air  leak  in 
that  cylinder. 


282  GAS,  OIL  AND  STEAM  ENGINES 

WATER  in  gasoline  will  cause  misfiiing,  especially  in  freez- 
ing weather,  as  it  obstructs  the  flow  of  fuel  to  the  carburetor. 
The  carburetor  and  tank  should  be  drained  at  regular  inter- 
vals, and  if  possible,  a  strainer  should  be  introduced  in  the 
gasoline  line. 

CLOGGED  NOZZLE.  Particles  of  loose  dirt  in  the  nozzle 
will  occasion  an  intermittent  flow  of  gasoline  that  will  result 
in  misfiring.  The  nozzle  should  be  cleaned  with  a  small  wire 
run  back  and  forth  throughout  the  opening. 

CLOGGED  AIR  VENT  in  the  float  chamber  will  change  the 
level  of  the  fuel,  and  will  either  "starve"  the  engine,  or  flood 
the  carburetor.  The  air  in  the  float  chamber  is  a  very  small 
hole,  and  is  likely  to  clog. 

HOT  FUEL  PIPE.  If  the  fuel  pipe  that  connects  the  tank 
with  the  carburetor,  becomes  hot,  due  to  its  proximity  to  the 
exhaust  pipe  of  cylinders,  vapor  will  be  formed  in  the  pipe 
that  will  interfere  with  the  flow  of  fuel. 

DIRT  UNDER  AUXILIARY  AIR  VALVE  will  prevent 
the  valve  from  seating  properly,  causing  the  engine  to  misfire 
at  low  speed. 

CRACKS  OR  LEAKS  in  intake  pipe  or  gaskets  will  cause 
intermittent  leaks  of  air  and  spasms  of  misfiring.  Old  cracks 
that  have  been  brazed  will  sometimes  open  and  close  alter- 
nately causing  baffling  cases  of  spasmodic  misfiring. 

DIRT  IN  AIR  INTAKE  will  change  the  air  ratio,  and  the 
increased  suction  will  cause  a  greater  flow  of  gasoline.  Do  not 
place  the  end  of  the  inlet  pipe  in  a  dusty  place,  nor  where  oil 
can  be  splashed  into  it  by  the  engine.  Clean  out  periodically. 

"LOADING  UP"  of  the  inlet  piping  in  cold  weather  on 
light  load  is  caused  by  the  mixture  condensing  in  the  intake 
pipe.  The  only  remedy  is  to  keep  the  piping  warm,  or  to 
heat  the  inlet  air. 

CLOGGED  OVERFLOW  PIPE,  with  engines  equipped 
with  pump  supply  will  cause  flooding,  as  the  fuel  does  not 
return  rapidly  enough  to  the  tank. 

(114)  Kerosene  Vaporizer  for  Motorcycles. 

An  ingenious  vaporizing  device  has  been  designed  for  the 
use  of  kerosene  as  a  fuel  for  motorcycle  engines,  by  the  M.  G. 
and  G.  Motor  Patents  Syndicate,  Ltd.,  England,  is  described  in 
Motor  Cycling.  The  device  consists  of  a  comminuter,  or  vapor- 
izer, which  screws  into  the  sparkling-plug  hole  in  the  cylinder, 
the  plug  being  transferred  to  an  aperture  in  the  vaporizer,  a 


GAS,  OIL  AND  STEAM  ENGINES  283 

feeder  for  regulating  the  supply  of  fuel  to  the  vaporizer,  and  a 
throttle  and  air  barrel,  or  mixing  chamber,  for  the  purpose  of 
proportioning  the  amount  of  air  and  gas  supplied  to  the  en- 
gine, and  for  controlling  the  speed  of  the  machine  as  in  an 
ordinary  carburetor. 

The  feeder  receives  the  fuel — in  this  case  kerosene — although 
any  heavy  oil  can  be  used  with  almost  equally  good  results. 
The  feeder  answers  a  purpose  similar  to  the  ordinary  float 
chamber  of  the  carburetor,  i.  e.,  to  regulate  the  amount  of  kero- 
sene it  is  required  to  pass  through  the  vaporizer.  It  consists 
of  a  small  chamber  mounted  upon  the  end  of  a  pipe  leading  to 
the  vaporizer.  Kerosene  is  fed  to  this  device  by  a  copper  pipe 
from  the  tank,  and  enters  at  the  lowest  point  through  a  3/16- 
inch  hole  or  jet.  This  is  covered  by  a  small  valve,  operated 
by  engine  suctiofl.  The  lift  of  this  valve  can  be  adjusted  by  the 
insertion  of  washers  to  suit  any  particular  size  of  engine,  just 
as  one  would  use  various  size  jets  to  suit  either  a  large  or  small 
engine.  One  of  the  greatest  advantages  of  the  device  lies  in 
the  size  of  this  aperture  or  jet,  inasmuch  as  it  cannot  possibly 
choke  up  with  grit,  and  even  water  will  pass  through  and  not 
stop  the  operation  of  the  carburetor.  At  the  top  of  the  feeder 
is  an  air  hole,  which  admits  just  sufficient  air  to  pass  the  kero- 
sene through  the  vaporizer,  the  reason  for  this  being  that  the 
heat  of  the  vaporizer  shall  only  act  upon  the  fuel,  the  mixture 
afterwards  being  balanced  by  air  being  admitted  through  the 
mixing  chamber. 

After  the  kerosene  leaves  the  feeder  it  passes  through  a  pipe 
to  the  vaporizer.  This  consists  of  a  gunmetal  body  with  cool- 
ing ribs  cast  on  the  outside,  whilst  through  the  center  runs  a 
thin  copper  tube  of  ^-inch  diameter  and  only  20  gauge,  which 
would  really  melt  during  the  heat  of  combustion  were  it  not 
for  the  fact  of  the  fuel  passing  through  it.  The  heat  derived 
from  this  formation  of  vaporizer  is  approximately  1,000  degrees 
Fahr.  Inside  the  central  tube  is  a  strip-steel  spiral,  which  serves 
the  double  purpose  of  giving  a  centrifugal  motion  to  the  fuel, 
and  at  the  same  time  forming  a  supporter  for  the  tube,  prevent- 
ing it  crushing  under  the  force  of  the  explosions.  It  is,  of 
course,  understood  that  the  inside  of  the  feeding  tube  is  en- 
tirely isolated  from  the  combustion  chamber.  The  sparking 
plug  is  screwed  into  the  wall  of  the  vaporizer,  which  is  now 
really  an  extension  of  the  combustion  chamber. 

Obviously  this  slightly  reduces  the  compression  of  the  en- 
gine, which,  however,  is  a  necessary  feature  when  kerosene  is 


284 


GAS,  OIL  AND  STEAM  ENGINES 


used  as  a  fuel.  After  passing  through  this  device  the  kerosene 
is  thoroughly  vaporized,  and  the  vapor  is  led  through  a  flexible 
pipe  to  the  throttle  chamber;  this  taking  the  place  of  an  ordinary 
carburetor  and  being  fitted  to  the  induction  pipe. 

There  are  two  slides,  operated  by  Bowden  levers  from  the 
handle-bar,  one  being  for  the  main  air  intake  and  the  other  for 
the  gas. 

Undoubtedly  the  greatest  claim  for  this  vaporizer  is  the  fact 
that  practically  no  carbon  deposit  forms  upon  the  inside  of  the 


Fig.    121-a.     The    English   Aster    Electric    Lighting  Unit. 

cylinder  or  on  the  piston.  What  little  deposit  is  formed  takes 
the  shape  of  small,  soft  flakes,  which,  instead  of  adhering  to  the 
cylinder  walls,  break  away  before  they  have  attained  any  size 
and  are  blown  through  the  exhaust  valve.  Altogether,  this  de- 
vice seems  to  have  finally  solved  the  problem  of  using  kerosene 
as  a  fuel  on  air-cooled  engines,  especially  if  the  carbon  deposit 
difficulty  has  been  finally  overcome. 

The  device  was  fitted  to  a  Zl/2  h.  p.'  Matchless  with  a  White 
and  Poppe  engine.  In  order  to  start  up,  a  small  gasoline  tank, 
holding  about  one  half-pint  of  gasoline,  is  fitted  under  the 
main  tank  and  communicates  with  the  feeder.  Half  a  minute 
is  all  that  is  necessary  running  on  gasoline,  when  the  kerosene 
can  be  turned  on.  The  machine  would  fire  at  a  walking  pace, 
and  could  also  be  accelerated  up  to  55  m.p.h. 


CHAPTER  X 
LUBRICATION 

(116)  General  Notes  on  Lubrication. 

No  matter  how  carefully  the  surface  of  a  shaft  or  bearing 
may  be  finished,  there  always  remains  a  slight  roughness  or  burr 
of  metal,  which  although  of  microscopic  proportions  is  produc- 
tive of  friction  or  wear.  Each  minute  projection  of  metal  on  a 
dry  shaft  acts  exactly  as  a  lathe  tool,  when  the  shaft  revolves 
in  cutting  a  groove  in  the  stationary  bearing.  Since  there  are 
a  multitude  of  these  projections  in  a  journal,  the  wear  would 
be  very  rapid,  and  would  in  a  short  time  completely  destroy 
either  the  shaft  or  bearing,  no  matter  how  highly  finished  in 
the  beginning. 

When  lubricating  oil  is  introduced  into  a  bearing  it  imme- 
diately covers  the  rubbing  surface,  and  as  the  oil  has  a  con- 
siderable resistance  to  being  deformed,  or  is  "stiff,"  it  separates 
the  surface  of  the  shaft  from  that  of  the  bearing  for  a  distance 
equal  to  the  thickness  of  the  oil  film.  With  ordinary  lubricants 
this  distance  is  more  than  enough  to  raise  the  irregularities  of 
the  shaft  out  of  engagement  with  those  of  the  bearing.  This 
property  of  "stiffness"  in  the  oil  is  known  as  "viscosity."  The 
value  of  viscosity  varies  greatly  with  different  grades  of  oil, 
and  also  with  the  temperature  with  the  result  that  the  allowable 
pressure  on  the  oil  per  square  inch  also  varies.  With  oils  of 
low  viscosity  a  small  pressure  per  square  inch  on  the  bearing 
will  squeeze  it  out,  and  allow  the  two  metallic  surfaces  to  come 
against  into  contact,  causing  wear  and  friction,  while  an  oil  of 
greater  viscosity  will  successfully  resist  the  pressure. 

The  life  and  satisfactory  operation  of  the  engine  depends  al- 
most entirely  upon  the  lubricant  and  the  devices  that  apply  it 
to  the  bearings.  Excessive  wear  and  change  in  the  adjust- 
ments are  nearly  always  the  result  of  defective  lubricating  de- 
vices or  a  poor  lubricant.  The  principal  lubricants  are: 

(1)  Solid  lubricants  such  as  graphite,  soapstone,  or  mica. 

(2)  Semi-solid  lubricants  such  as  vaseline,  tallow,  and  soap 

285 


286  GAS,  OIL  AND  STEAM  ENGINES 

emulsions,  or  greases  compounded  of  animal  fats,  vegetable  and 
mineral  oils;  and 

(3)  Liquid  lubricants,  such  as  sperm  oil,  or  one  of  the  prod- 
ucts of  petroleum,  the  latter  medium  being  the  class  of  lubri- 
cant ,most  suitable  for  internal  combustion  engines,  owing  to  its 
combining  the  qualities  of  a  high  flash-point  with  a  compara- 
tive freedom  from  either  acidity  or  causticity. 

Oils  of  animal  or  vegetable  origin  should  never  be  used 
with  gas  engine  as  the  high  temperatures  encountered  will 
char  and  render  them  useless.  Tallow  and  lard  oil  are  especially 
to  be  avoided,  at  least  in  a  pure  state.  . 

In  the  cylinder  only  the  best  grade  of  GAS  ENGINE  cyl- 
inder oil  should  be  used,  which  according  to  different  makers 
has  a  flash  point  ranging  from  500  to  700  degrees.  Using  cheap 
oil  in  the  cylinder  is  an  expensive  luxury.  In  general,  the  oils 
having  the  highest  flash  points  have  also  the  objectionable  ten- 
dency of  causing  carbon  desposits  in  the  combustion  chamber 
and  rings  which  is  productive  of  preignition  and  compression 
leakage.  The  lower  flash  oils  have  a  tendency  to  vaporize  and 
to  carry  off  with  the  exhaust  which  will  leave  the  walls  insuffi- 
ciently lubricated  unless  an  excessive  amount  is  fed  to  the  cyl- 
inder. By  starting  with  samples  of  well  known  brands  rec- 
ommended by  the  builder  of  the  engine  it  will  be  an  easy  mat- 
ter to  find  which  is  the  cheapest  and  gives  the  best  results. 
In  figuring  the  cost  of  oil  do  not  take  the  cost  per  gallon  as  a 
basis,  but  the  cost  for  so  many  hours  of  running,  or  better  yet 
the  number  of  horse-power  hours.  Unless  you  are  fond  of  buy- 
ing replacements  and  new  parts  do  not  stint  on  the  oil  supply. 

On  the  other  hand,  an  excess  of  oil  should  be  avoided  as 
this  means  not  only  a  waste  of  oil  through  the  exhaust  pipe, 
but  trouble  with  carbon  deposits  and  ignition  troubles  as  well. 
Foul  igniters,  misfiring,  and  stuck  piston  rings  are  the  inevitable 
result  of  a  flood  of  lubricating  oil.  When  a  whitish  yellow 
cloud  of  smoke  appears  at  the  end  of  the  exhaust  pipe,  cut 
down  the  oil  feed.  The  exhaust  should  be  colorless  and  prac- 
tically odorless. 

Too  much  oil  cannot  be  fed  to  the  main  bearings  of  the  crank 
shaft  if  the  waste  oil  is  caught,  filtered  and  returned  to  the 
bearings  by  a  circulating  system,  for  the  flood  of  oil  not  only 
insures  ample  lubrication  but  removes  the  heat  generated  as 
well.  The  bearings  require  a  much  lighter  oil,  of  a  lower 
fire  test  than  the  cylinder  oil.  It  is  evident  that  its  viscosity 
is  a  most  important  element,  as  it  determines  the  allowable 


GAS,  OIL  AND  STEAM  ENGINES  287 

pressure  on  the  shaft.  The  viscosity  of  an  oil  varies  with  the 
temperature  and  is  greatly  reduced  at  cylinder  heat.  A  com- 
parative test  of  the  viscosity  or  load  bearing  qualities  of  an  oil 
may  be  made  by  making  bubbles  with  it  by  means  of  a  clay 
pipe;  the  larger  the  bubble,  the  higher  the  viscosity  of  the  oil. 

Different  sizes  of  bearings,  and  bearing  pressures,  call  for  oils 
of  different  viscosities,  and  consequently  an  oil  that  would  be 
suitable  for  one  engine  would  not  answer  for  another;  heavy 
bodied  oils  being  used  for  heavy  bearing  pressures,  and  light 
thin  oil  for  small  high  speed  bearings.  The  best  way  to  deter- 
mine the  value  of  an  oil  for  a  particular  shaft  bearing  is  by 
experiment,  attention  being  paid  to  its  adaptability  for  the 
feeding  devices  used. 

The  compression  attained  in  a  gas  engine  cylinder  depends  to 
a  certain  extent  upon  the  body  of  the  cylinder  oil,  for  many 
engines  that  leak  compression  past  the  rings  with  thin  oil  will 
work  satisfactorily  with  a  heavy  viscuous  oil  that  clings  tightly 
to  the  surfaces.  An  engine  will  often  lose  compression  when 
an  oil  of  poor  quality  is  used. 

Air  cooled  engine  cylinders  require  an  oil  of  heavier  body 
than  water  cooled  because  of  the  higher  temperature  of  the 
cylinder  walls.  Gum  and  sticky  residue  are  usually  formed  by 
animal  oils  or  adulterants  added  to  the  numeral  oil  base.  Oils 
containing  free  acids  should  be  avoided  as  they  not  only  cor- 
rode and  etch  the  bearing,  but  also  clog  the  oil  pipes  or  feeds 
with  the  products  of  the  corrosion. 

Free  acid  is  left  from  the  refining  process,  and  may  be  deter- 
mined by  means  of  litmus  paper  inserted  into  the  oil.  If  the 
litmus  paper  turns  red  after  coming  into  contact  with  the  oil, 
acid  is  present,  and  the  oil  should  be  rejected. 

The  following  are  the  characteristics  of  an  oil  suitable  for 
use  on  an  engine: 

(a)  The  oil  must  be  viscous  enough  to  properly  support  the 
bearings  or  to  prevent  leakage  past  the  piston  rings. 

(b)  It    should   be    thin    enough    so    that   it    can    be    properly 
handled  by  the  oil  pumps,  or  drip  freely  in  the  oil  cups. 

(c)  It  should  not  form  heavy  deposits  of  oil  in  the  cylinder 
and  cause  the  formation  of  "gum." 

(d)  It  should  contain  no  free  acid. 

Ordinarily  a  good  grade  of  fairly  heavy  machine  oil  will  be 
suitable  for  use  on  the  bearings  of  the  average  engine,  such  as 
the  cam-shaft  and  crank-shaft  bearings. 

Only  very  light  clean  oil,  or  vaseline  should  be  used  on  ball- 


288  GAS,  OIL  AND  STEAM  ENGINES 

bearings,  as  heavy  greases  and  solid  lubricants  pack  in  the 
races  and  cause  binding  or  breakages. 

Flake  graphite  is  much  used  as  lubricant,  and  too  much  can- 
not be  said  in  its  favor,  as  it  furnishes  a  smooth,  even  coat  over 
the  shaft,  fills  up  small  scores  and  depressions,  and  makes  the 
use  of  light  oil  possible  under  heavy  bearing  pressures.  With 
graphite,  less  oil  is  used,  as  the  graphite  is  practically  perma- 
nent, and  should  the  oil  fail  for  a  time,  the  graphite  coat  will 
provide  the  necessary  lubrication  until  the  feed  is  resumed 
without  danger  of  a  scoring  or  cutting.  In  fact,  when  graphite 
is  used,  the  oil  simply  acts  as  medium  by  which-  the  graphite 
is  carried  to  the  bearings. 

If  graphite  is  injected  into  the  cylinder  in  small  quantities  it 
greatly  improves  the  compression,  as  it  fills  up  all  small  cuts 
and  abrasions  in  the  cylinder  walls. 

A  good  mixture  to  use  for  bearings  is  about  \l/2  teaspoonsful 
of  graphite,  to  a  pint  of  light  machine  oil,  thoroughly  mixed. 

Graphite  can  be  placed  in  the  crank  chamber  of  a  splash  feed 
engine,  by  means  of  an  insect  powder  gun. 

Trouble  with  oil  cups  is  always  in  evidence  during  cold 
weather,  as  the  oil  congeals,  and  does  not  drip  properly  into 
the  bearings.  The  fluidity  of  the  oil  can  be  increased  in  cold 
weather  by  the  addition  of  about  ten  per  cent  of  kerosene  to 
the  oil. 

If  too  much  oil  is  fed  to  the  cylinders,  the  piston  rings  will 
be  clogged  with  gum,  and  a  loss  of  compression,  or  a  tight 
piston  will  be  the  result.  An  excess  of  oil  will  short-circuit 
the  igniter  or  sharp  plugs,  and  will  form  a  thick  deposit  in  the 
combustion  chamber  that  will  eventually  result  in  preignition 
or  back-firing.  Deposits  and  gum  formed  in  the  cylinder  will 
cause  leaky  valves  and  a  loss  of  compression.  Feed  enough 
oil  to  insure  perfect  lubrication,  but  not  enough  to  cause  light 
colored  smoke  at  the  exhaust. 

Lubricating  systems  may  be  divided  into  three  principal 
classes:  Sight-feed,  splash  system,  and  the  force  feed  system. 
Sight  feeding  by  means  of  dripping  oil  cups  is  too  common  to 
require  description,  and  is  used  on  many  stationary  engines, 
both  large  and  small. 

The  splash  system  is  in  general  use  on  small  high  speed 
engines  both  stationary,  and  of  the  automobile  type. 

The  force  feed  system  in  which  oil  is  fed  under  pressure  by 
a  pump  is  by  far  the  most  desirable  as  the  amount  of  oil  fed 
is  given  in  positive  quantities  proportional  to  the  engine  speed, 


GAS,  OIL  AND  STEAM  ENGINES  289 

and  with  sufficient  pressure  to  force  it  past  any  ordinary  ob- 
structions that  may  exist  in  the  oil  pipe. 

Another  system  that  is  half  splash,  and  half  force  feed,  is  the 
pump  circulated  system  much  used  in  automobiles. 

THE  SPLASH  FEED  SYSTEM  is  the  simplest  of  all,  as 
the  bearings  are  lubricated  by  the  oil  spray  caused  by  the  con- 
necting rod  end  splashing  through  an  oil  puddle  located  in 
the  bottom  of  the  closed  crank  case.  The  piston  and  cylinder 
are  lubricated  by  the  spray,  as  well  as  the  bearings,  as  the 
lower  end  of  the  piston  projects  into  the  crank  chamber  at  the 
moment  that  the  connecting  rod  end  strikes  the  oil  puddle. 

To  maintain  constant  lubrication,  it  is  necessary  that  the  oil 
in  the  puddle  be  kept  at  a  constant  height,  or  as  in  some  cases 
be  varied  in  such  a  way  that  the  surface  of  the  puddle  is  raised 
and  lowered  in  proportion  to  the  load  on  the  engine.  In  the 
average  engine  the  oil  level  is  maintained  by  overflow  pipes 
or  openings  that  allow  any  excess  of  oil  over  the  fixed  level 
to  flow  back  to  the  pump.  In  the  Knight  engine  the  puddles 
are  formed  in  movable  cups  which  are  connected  with  the 
throttle  in  such  a  way  that  the  opening  of  the  throttle  raises 
the  oil  level  and  supplies  more  oil  to  the  engine  at  the  greater 
load,  or  speed. 

Oil  in  splash  systems  is  supplied  by  a  low  pressure  pump, 
usually  of  the  rotary  type,  in  the  base  of  the  engine.  Oil  from 
the  pump  passes  to  the  bearings,  drops  into  the  puddle,  over- 
flows through  the  overflow  opening,  and  returns  to  the  pump 
through  a  filter,  the  same  oil  being  used  over  and  over  again 
until  exhausted.  This  strainer  should  be  removed  occasionally 
and  the  dirt  removed,  for  should  it  be  allowed  to  collect  it  is 
likely  to  obstruct  the  oil  supply.  The  oil  should  be  replaced 
before  it  becomes  too  black  or  foul,  the  crank  case  and  bear- 
ings thoroughly  cleaned  with  kerosene,  and  new  oil  replaced. 
The  supply  may  be  interrupted  by  the  failure  of  the  pump, 
caused  by  sheared  keys  or  leakage  of  air  in  the  suction  line  due 
to  cracks.  It  would  be  well  to  run  the  engine  for  a  few  min- 
utes with  the  kerosene  in  the  crank  case,  in  order  that  all  of 
the  oil  may  be  removed.  See  that  the  drain  cock  is  closed  at 
the  bottom  of  the  cylinder  or  all  of  the  oil  will  be  lost.  Lock 
the  valve  handle  carefully  so  that  it  cannot  jar  open.  If  light 
colored  smoke  appears  in  intermittent  puffs  with  a  multiple 
cylinder  engine,  it  indicates  that  one  cylinder  is  receiving  too 
much  oil. 


290  GAS,  OIL  AND  STEAM  ENGINES 

(117)  Force  Feed  Lubricating  System. 

The  force  feed  system  is  by  far  the  most  reliable  of  all  oil- 
ing systems,  as  it  feeds  uniformly  and  continuously  at  almost 
any  temperature,  and  against  the  pressure  of  practically  any  ob- 
struction in  the  pipe. 

The  oil  is  supplied  by  a  small  pump  driven  from  the  engine, 
the  pump  being  incased  in  the  oil  tank  housing.  Frequently 
a  hand  pump  is  used  in  combination  with  the  power  pump  when 
starting  the  engine,  or  at  times  when  the  power  pump  is  out 
of  service.  A  single  pump  is  used  with  any  number  of  leads, 
each  lead,  of  feed,  having  an  independent  regulating  valve  and 
sight  feed,  or  a  pump  unit  may  be  provided  for  each  lead, 
depending  on  the  size  of  the  engine. 

(118)  Bosch  Force  Feed  Oiler. 

The  force  feed  of  the  Bosch  Oiler  is  so  positive  in  character, 
that  the  flow  of  oil  is  not  affected  by  heavy  back-pressure  due 
to  elbows  and  the  diameter  of  the  conducting  pipes.  Springs, 
valves  and  other  devices,  which  would  check  the  flow  of  oil, 
are  fundamentally  eliminated.  The  amount  of  oil  fed  may  be 
accurately  and  permanently  regulated.  Glands  and  other  pack- 
ings and  bushings  are  eliminated.  Connecting  rods  and  all 
links  are  eliminated  by  the  direct  application  of  the  movements 
of  the  oscillating  cam  disks  to  the  pump  plungers  and  piston 
valves. 

Each  feed  of  this  oiler  is  provided  with  a  separate  pump  ele- 
ment consisting  of  a  pump  body  plunger  and  a  piston  valve, 
the  suction  and  feed  ducts  connecting  directly  with  the  pump 
body  of  their  respective  elements.  With  this  construction, 
pump  elements  may  be  replaced  or  added.  The  oiler  requires 
no  attention  other  than  to  be  supplied  with  oil;  and  the  open- 
ing and  closing  of  the  valves,  pet  cocks,  etc.,  on  starting  and 
stopping  the  machine  is  rendered  unnecessary.  The  correct 
and  regular  operation  of  the  elements  may  be  verified  by  ob- 
servation of  the  reciprocating  movements  of  the  regulating 
screws. 

Each  pump  plunger  is  provided  with  an  adjusting  screw 
through  which  the  feed  may  be  regulated  from  0  to  0.2  cubic 
centimeters  for  each  stroke. 

The  Bosch  Oiler  (Fig.  121)  being  positively  driven  by  the 
machine  that  it  supplies,  the  oil  fed  is  in  all  cases  proportional 
to  the  engine  speed;  overloads  are  thus  automatically  taken 
care  of. 


GAS,  OIL  AND  STEAM  ENGINES 


291 


The  circular  arrangement  of  the  elements  of  the  Bosch 
Oiler  permits  the  device  to  be  driven  by  a  single  shaft,  and 
the  oil  is  forced  through  the  feeds  from  a  single  reservoir  to 
the  required  points  of  application.  A  pump  element  consists 
of  a  pump  body  1,  a  pump  plunger  2  and  a  piston  valve  3, 
and  is  supported  on  the  base  plate  13.  The  elements  are  ar- 


20  "•  13 

Top  View  of  Bosch  Force  Feed  Oiler. 

ranged  concentrically  about  the  drive  shaft  in  such  a  manner 
that  the  pump  plungers  form  a  circle  around  the  circle  formed 
by  the  piston  valves. 

The  pump  cam  disk  20  and  the  valve  cam  disk  22  are  set  on 
the  drive  shaft  at  other  than  a  right  angle  with  its  axis,  and 
the  rims  of  the  disks  are  gripped  by  slots  formed  in  the  heads 


-36 


25 

Fig.    121.     Cross-Section    Bosch    Oiler. 

of  the  pump  plungers  and  piston  valves.  The  relation  of  these 
cam  disks  is  such  that  the  valve  cam  disk  is  90°  in  advance 
of  the  plunger  cam  disk.  The  valve  ca^ri  disk  is  solid  on  the 
drive  shaft,  but  the  pump  cam  shaft  is  Voose  and  driven  through 
a  lug  on  the  valve  cam  disk.  When  the  drive  of  the  pump  is 


292  GAS,  OIL  AND  STEAM  ENGINES 

reversed,  the  lug  on  the  valve  cam  disk  frees  itself  and  again 
takes  up  the  drive  of  the  pump  cam  disk,  after  the  drive  shaft 
has  made  a  half  revolution. 

Regulating  screws  4  are  set  in  the  slotted  heads  of  the  pump 
plunger,  and  by  means  of  this  the  back-lash  or  play  of  the 
cam  disk  may  be  regulated.  The  regulating  screws  are  pro- 
vided with  lock  nuts,  and  project  through  the  cover  of  the  oil 
tank  housing,  being  exposed  by  the  removal  of  the  filler  cover 
42.  The  filler  opening  is  provided  with  a  removable  strainer 
to  prevent  the  entrance  of  foreign  particles  into  the  oil  tank. 

Pump  shaft  14  is  driven  through  worm  gear  23  which  meshes 
with  worm  24  on  drive  shaft  25;  drive  shaft  25  projects  from  the 
oiler  housing,  and  is  coupled  with  the  driving  shaft  of  the 
machine  to  be  lubricated. 

Base  plate  13  is  attached  to  the  oiler  cover  by  three  stud 
bolts,  thus  permitting  the  removal  of  the  entire  oiler  mechanism 
from  the  housing. 

The  quanitity  of  oil  in  the  oil  tank  is  shown  by  gauge  glass  44. 

On  the  starting  of  the  machine  to  which  the  oiler  is  attached, 
the  pump  shaft  and  the  cam  disks  that  it  supports  are  set  in 
motion  through  worm  24  and  worm  gear  23.  A  direct  recipro- 
cating motion  is  given  to  the  pump  plunger  and  to  the  piston 
valve  by  the  rotation  of  the  cam  disks  which  have  a  move- 
ment similar  to  that  of  the  "wobble  saw."  The  relation  of  the 
cam  disk  is  such  that  the  piston  valve  movements  are  90°  in 
advance  of  the  movements  of  the  pump  plungers.  The  pump 
will  run  in  either  direction  without  alteration. 

•  To  secure  this  effect  a  play  of  90°  is  provided  between  the 
cam  disk.  When  cam  22  is  driven  clockwise,  cam  disk  20  is 
driven  by  the  lug  which  meshes  with  a  lug  on  disk  22.  The 
cams  are  then  in  such  a  relation  that  the  cam  valve  disk  is  90° 
in  advance  of  the  pump  cam  disk.  When  reversed,  cam  20  re- 
mains at  rest  until  cam  22  catches  the  lug  and  cam  20,  when 
the  drive  continues  as  before.  The  cams  are  then  in  the  same 
relation  as  previously  for  as  the  valve  disk  22  has  traveled 
through  180°  it  is  evident  that  it  is  90°  in  advance  of  the  pump 
disk. 

(119)  Castor  Oil  for  Aero  Engines. 

Castor  oil  is  used  almost  exclusively  in  the  Gnome  and  other 
rotary  engines  of  the  same  type,  but  has  not  been  particularly 
successful  on  stationary  cylinders. 

Chemically,  castor  oil  differs  from  all  other  vegetable  or  ani- 


GAS,  OIL  AND  STEAM  ENGINES  293 

mal  oils  in  containing  neither  palmitine  or  olein.  It  is  soluble 
in  absolute  alcohol,  but  practically  insoluble  in  gasoline.  On 
the  other  hand,  the  castor  oil  is  capable  of  dissolving  small 
quantities  of  mineral  oil,  the  more  fluid  they  are  the  less 
it  absorbs  of  them.  But  the  insolubility  of  castor  oil  in  min- 
eral oil  disappears  completely  when  it  is  mixed  with  even  a 
very  small  quantity  of  another  vegetable  or  animal  oil,  such  as 
colza  or  lard  oil.  An  adulteration  may  thus  result  in  a  serious 
reversal  of  the  oil's  best  qualities;  in  fact,  in  serious  seizures. 
Castor  oil  does  not  attack  rubber,  but  it  contains  1  to  2  per 
cent  of  acid  fats;  sometimes  more. 

"In  my  opinion  says  a  writer  in  'Autocar'  castor  oil  can 
only  be  used  in  fixed  cylinders  with  impunity  for  short  distances 
and  then  with  repeated  cleanings  between  runs,  but  on  rotary 
engines  of  the  Gnome  type  cleaning  is  almost  unnecessary.  The 
reason  is  that  one  cannot  .consistently  use  castor  oil  over  and 
over  again,  for  the  fact  is  indisputable  that  it  has  a  far  greater 
tendency  than  mineral  oils  to  absorb  oxygen,  and  so  gradually 
to  increase  in  body  and  finally  to  gum.  When  once  it  com- 
mences to  gum  the  carbonization  becomes  more  rapid,  because 
the  thickened  and  pitch-like  oil  acts  as  an  insulating  covering 
on  the  top  of  the  pistons  and  of  the  cylinder,  and  cannot  get 
away  with  sufficient  rapidity  to  avoid  decomposition  and  bak- 
ing to  a  coke.  Therefore  if  castor  oil  is  to  be  used  on  the 
ordinary  stationary  cylinder  type  of  engine,  it  is  necessary  to 
wash  out  the  crank  chamber  and  to  replace  with  fresh  oil  at 
frequently  intervals.  On  a  rotary  engine  such  as  the  Gnome  this 
cleaning  is  unnecessary,  because  there  is  a  continuous  stream 
of  fresh  castor  oil  brought  into  the  crank  chamber  and  then 
thrown  by  centrifugal  force  past  the  pistons  and  through  the 
cylinder  into  the  exhaust.  Thus  the  stream  of  oil  never  has 
sufficient  time  to  oxidize  fully,  gum  or  decompose.  This  action 
of  centrifugal  force  accounts  for  the  large  consumption  of  oil 
on  the  rotary  engine,  and  also  for  the  fact  that  the  pistons  and 
cylinders  keep  comparatively  clean. 

"In  thus  criticizing  the  use  of  castor  oil  I  do  not  wish  it  to 
be  inferred  that  it  is  not  an  excellent  lubricant.  What  I  wish 
to  suggest  is  that  in  the  case  of  an  internal  combustion  engine 
it  must  be  made  with  discretion.  A  point  in  favor  of  castor  oil 
is  the  fact  that  it  maintains  is  viscosity  in  a  remarkable  man- 
ner at  high  temperatures,  and  that  at  those  high  temperatures 
it  has  a  peculiar  creeping  or  capillary  action  which  enables  it 
to  spread  uniformly  over  the  whole  of  the  metallic  surfaces. 


294 


GAS,  OIL  AND  STEAM  ENGINES 


whereas  under  the  same  conditions  a  similarly  bodied  mineral 
oil  would  be  unevenly  distributed  in  patches.  Another  point  is 
that  the  specific  heat  of  castor  oil  is  considerably  higher  than 
that  of  a  pure  mineral  oil.  This  is  in  its  favor,  insomuch  that 
it  shows  castor  oil  to  be  a  better  heat  remover  than  a  mineral 
oil. 

"Motorists  and  aviators  have  from  time  to  time  informed  me 
that  they  are  using  castor  oil,  but  have  apparently  been  under 
some  misapprehension.  I  find  that  they  have  been  using  a 
brand  of  prepared  oil  under  the  impression  that  it  is  a  specially 
refined  castor  oil,  or  that  it  is  a  blend  of  castor  oil." 


Producer    Gas    Engine    Plant    at    Gottingen,    Germany,    Consisting    of 
Four  3,500  Horse-Power  Units. 

A  simple  method  for  testing  the  purity  of  castor  oil  is  at 
the  disposal  of  all.  It  is  known  as  the  Finkener  test.  Ten 
cubic  centimeters  of  castor  oil  is  placed  in  a  graduate.  Five 
times  as  much  alcohol,  90  per  cent,  is  added  and  stirred  in.  The 
solution  should  remain  clear  and  brilliant  at  15  to  20  degrees 
C.  An  admixture  of  foreign  oils,  even  if  only  5  per  cent,  riles 
the  solution  at  this  temperature,  though  not  above  it. 

(120)  Force  Feed  Troubles. 

The  most  common  trouble  with  force  feed  systems  is  the  fail- 
ure of  the  operator  to  remove  the  dirt  collected  by  the  strainer. 
The  oil  piping  should  be  cleaned  out  at  least  once  every  year 
by  means  of  a  wire  and  gasoline,  to  remove  any  gum  that 
inay  have  been  deposited.  Driving  belts  should  be  kept  tight 


GAS,  OIL  AND  STEAM  ENGINES        295 

to  prevent  slipping,  and  belts  that  are  soaked  with  oil  should 
be  cleaned  with  gasoline  and  readjusted. 

Leaking  pump  valves  generally  of  the  ball  type  are  a  com- 
mon cause  of  failure.  They  may  leak  because  of  wear  or  by 
an  accumulation  of  grit  and  dirt  on.  their  seats,  which  prevents 
the  valves  from  seating  properly.  If  the  valves  leak,*  the  oil 
will  be  forced  back  into  the  tank,  or  will  not  be  drawn  into 
the  pump  cylinder  at  all,  depending  on  whether  the  inlet  or 
discharge  valve  is  the  offender.  Plunger  leakage  which  is  rare 
will  cause  oil  failure. 

If  the  oil  pipes  that  lead  to  the  bearings  rub  against  any  mov- 
ing part,  or  against  a  sharp  edge,  a  hole  will  be  worn  in  the 
pipe,  a  leak  caused  which  will  prevent  the  oil  from  reaching  the 
bearing.  A  dented  or  "squashed"  pipe  will  prevent  the  flow  of 
oil. 

The  set  screw  or  pin  holding  the  pulley  to  the  pump  shaft 
may  loosen  and  cause  it  to  run  idly  on  the  shaft  without  turn- 
ing the  pump.  This  will  of  course,  prevent  the  circulation  of  oil. 

The  worm  and  worm  wheel  may  wear  so  that  the  pump  is 
no  longer  driven  by  the  pulley  shaft,  or  a  poor  pipe  connection 
may  leak  all  that  the  pump  delivers. 

The  amount  of  oil  required  by  each  lead-  or  bearing  should 
be  carefully  determined  by  experiment,  and  kept  constantly  at 
the  right  number  of  drops  per  minute. 

The  feed  adjustments  jar  loose,  and  should  be  inspected  fre- 
quently. 

(121)  Oil  Cup  Failure. 

Oil  cups  should  be  cleaned  out  frequently  with  gasoline  or 
kerosene,  as  any  gum  or  lint  will  interfere  seriously  with  the 
feed.  They  should  be  adjusted  and  filled  frequently  to  prevent 
any  possible  chance  of  a  hot  bearing. 

Oil  cups  should  be  as  large  as  possible  in  order  that  they  may 
be  left  for  considerable  periods  without  danger  of  a  hot  box. 

Cold  weather  affects  the  oil  feed  to  a  considerable  extent, 
especially  with  small  oil  cups,  and  they  should  be  kept  as  warm 
as  possible.  When  heavy  oils  are  used  a  cold  draft  will  stop 
the  feed. 

Oils  may  be  made  more  fluid  in  cold  weather  by  the  addition 
of  about  ten  per  cent  of  kerosene. 

(122)  Hot  Bearings. 

A  hot  bearing  is  almost  a  sure  sign  of  insufficient  oil,  and 
the  trouble  should  be  located  and  remedied  immediately.  Oil 


296  GAS,  OIL  AND  STEAM  ENGINES 

pumps  stopping,  clogged  oil  pipes  or  holes,  frozen  oil,  or  oil 
leaks  are  common  causes  of  hot  bearings. 

Never  allow  an  engine  to  run  with  a  hot  bearing  for  any 
length  of  time,  as  the  bearing  or  piston  may  seize  tight  and 
wreck  the  engine.  Inspect  the  journals  frequently  to  see  if  they 
are  above  normal  temperature.  A  hot,  binding  bearing  often 
causes  the  effect  of  an  overload  on  the  engine,  slowing  it  down, 
and  increasing  the  governor  and  fuel  feed,  this  is  followed  in  a 
short  time  by  the  bearing  seizing. 

(123)  Cold  Weather  Lubrication. 

It  is  by  no  means  uncommon  trouble  in  cold  weather  to  find 
excessive  fluctuations  in  pressure  as  the  engine  speed  and  tem- 
perature of  the  oil  varies.  Thus,  if  the  pressure  be  set  correctly 
with  the  engine  running  fast,  and  when  just  started  up,  it  will 
be  found,  after  half-an-hour's  running,  that,  with  the  engine  turn- 
ing slowly,  the  pressure  is  far  too  low,  owing  to  the  oil  having 
become  thin.  If  the  pressure  be  then  reset,  it  may  be  found 
on  next  starting  up  from  cold  that  the  gauge  goes  hard  over, 
and  may  very  easily  be  burst  if  the  engine  is  run  fast. 

The  point  is  one  to  which  many  designers  of  engines  pay  far 
too  little  attention,  though  the  difficulty  may  be  very  easily 
gotten  over.  The  secret  lies  in  having  the  by-pass  outlet  of 
most  ample  proportions,  so  that  the  excess  of  oil,  however 
thick,  can  get  away  quite  easily.  If  there  is  any  throttling  of 
the  by-pass,  back  pressure  must  result  with  consequent  increase 
of  the  pressure  at  which  the  by-pass  valve  comes  into  opera- 
tion. In  other  words,  the  pressure  of  the  main  supply  to  the 
bearings  will  be  increased. 

A  writer  to  "The  Motor,"  London  solved  this  problem  in  the 
following  manner: 

"Originally,  the  by-passage  was  somewhat  small,  little  larger 
than  the  oil  delivery  pipe  to  the  engine,  which  was  about  3/16 
inch  bore,  and  the  result  was  that  the  pressure  when  starting 
with  the  oil  cold  rose  to  about  25  pounds  per  square  inch,  and 
fell  to  about  one  pound  per  square  inch  with  the  oil  hot  and 
the  engine  running  slow.  It  was  possible,  however,  to  bore 
out  the  by-pass  passage  and  fit  a  larger  pipe,  about  three  times 
the  area  of  the  main  delivery  pipe,  with  the  result  that 
the  oil,  when  cold,  never  rose  above  about  15  pounds  per 
square  inch,  however  fast  the  engine  run.  When  thor- 
oughly heated,  the  normal  running  pressure  was  about  6  pounds 
per  square  inch,  falling  to  2  pounds  per  square  inch  with 


GAS,  OIL  AND  STEAM  ENGINES 


297 


the  engine  only  just  turning  over,  which  brings  up  the  ques- 
tion of  the  correct  working  pressure.  This  will  vary  very 
largely  with  the  design  of  the  engine,  but,  broadly  speak- 
ing, the  higher  the  pressure  the  better  for  the  bearings.  The 
limiting  figure  is  determined  by  the  tendency  of  the  engine  to 
throw  out  oil  at  the  end  of  crankshaft  bearings,  and  by  the 
amount  that  gets  past  the  piston  rings.  Obviously,  an  engine 
with  new,  tight  bearings  and  new  piston  rings  will  stand  a 
higher  pressure  without  undue  waste  of  oil  or  excess  deposit 
in  the  cylinder  head  than  will  an  old  engine  with  worn  bearings 
and  slack  rings.  And,  again,  the  question  will  be  affected  by 


Brookes  Gasoline-Electric  Generating  Units  for  Operating  Search   Lights. 
An  Independent  Unit  is  Used  for  Each  Light. 

the  design  of  the  pistons.  For  instance,  where  the  trunk  of 
the  piston  is  bored  for  lightness,  much  more  oil  will  get  past 
the  rings  than  in  cases  where  a  'solid'  trunk  is  employed. 
Roughly  speaking,  8  to  15  pounds  per  square  inch  is  a  good 
figure  for  a  new,  high-speed  engine.  An  old  and  worn  engine, 
particularly  if  not  of  a  high-speed  type,  may  require  no  more 
than  2  to  6  pounds  per  square  inch." 

"The  writer  recently  encountered  a  rather  curious  difficulty  in 
connection  with  obtaining  a  free  by-pass.  The  return  pipe 
from  the  by-pass  led  into  the  case  carrying  the  gearwheels  of 
the  camshaft  and  magneto  drive,  and  oil  continually  flooded  out 


298  GAS,  OIL  AND  STEAM  ENGINES 

from  the  end  of  the  camshaft  and  other  bearings.  The  waste 
and  mess  were  sufficiently  serious  to  warrant  investigation,  and 
the  cover  plate  over  the  gears  was  accordingly  taken  off.  It 
was  then  noticed  that  the  oil  delivered  to  the  gearwheel  case 
had  only  two  small  holes  by  which  to  drain  away  to  the  crank- 
case.  The  flow  from  the  by-pass  was  beyond  the  proper  ca- 
pacity of  these  holes,  and  so  the  whole  gearwheel  case  became 
filled  with  oil  under  considerable  pressure,  quite  possibly  2  or  3 
pounds  per  square  inch,  and  it  was  not  surprising  that  oil  exuded 
from  the  ends  of  the  bearing.  A  few  extra  limber-holes,  if  one 
may  borrow  a  nautical  expression,  were  drilled  through  to 
the  crankcase,  and  no  further  trouble  was  experienced." 

(124)  Plug  Oil  Holes  When  Painting. 

When  the  chassis  of  the  car  is  repainted  it  is  well  to  see 
that  all  exposed  oil  holes  are  stuffed  with  waste  to  prevent 
them  from  being  choked.  Failure  to  observe  this  precaution 
may  result  in  the  holes  being  clogged  with  paint,  which  if  not 
removed  before  the  car  is  started,  will  prevent  oil  reaching  the 
bearings. 

(125)  Oiling  the  Magneto. 

Never  oil  the  circuit  breaker  or  circuit  breaker  mechanism, 
unless  for  a  drop  of  sperm  oil  that  may  be  applied  to  the  cam 
roller  by  means  of  a  toothpick.  If  oil  gets  on  the  circuit  breaker 
contact  points,  it  will  cause  them  to  spark  badly,  resulting  in 
pitting  or  destruction  of  the  points.  If  the  oil  is  occasionally 
applied  to  the  cam  roller  or  should  oil  accumulate  on  breaker 
points,  the  breaker  should  be  rinsed  out  with  gasoline  to  re- 
move the  surplus. 

Pitted  or  carbonized  contact  points  are  capable  of  causing 
much  trouble,  and  gummy  oil  or  dirt  will  develop  this  trouble 
quicker  than  any  other  cause.  Use  only  the  best  grade  of  thin 
sperm  oil  on  the  ball  bearings. 

In  the  course  of  time  the  circuit  breaker  contact  points  will 
wear  or  burn,  causing  imperfect  contact,  and  too  great  a  separa- 
tion between  the  points.  The  contacts  should  be  examined 
from  time  to  time,  and  if  rough  or  pitted,  should  be  dressed 
down  to  a  flat  even  bearing  by  means  of  a  dead  smooth  file, 
and  the  distance  readjusted.  The  contacts  should  not  bear  on 
a  corner  or  edge,  but  should  bear  evenly  over  their  entire  sur- 
face to  insure  a  maximum  primary  current  and  spark. 


CHAPTER  XI 
COOLING  SYSTEMS 

The  object  of  the  cooling  system  is  not  to  keep  the  cylinder 
cold,  but  to  prevent  the  heat  of  the  successive  explosions  from 
heating  the  cylinder  walls  to  a  degree  that  would  vaporize  the 
lubricating  oil  and  prevent  satisfactory  lubrication  of  the  cyl- 
inder and  piston.  The  hotter  the  cylinder  can  be  kept  without 
interfering  with  the  lubricating  oil,  the  higher  will  be  the  effi- 
ciency of  the  engine  and  the  greater  the  output  of  power. 

To  obtain  the  greatest  power  from  an  engine,  the  heat  devel- 
oped by  the  combustion  should  be  confined  to  the  gas  in  order 
that  the  pressure  and  expansion  be  at  a  maximum,  it  is  evident 
that  the  pressure  and  power  will  be  reduced  by  over-cooling 
as  the  heat  of  the  expanding  gas  will  be  taken  from  the  cyl- 
inder and  transferred  to  the  cooling  medium.  The  temperature 
of  the  cylinder,  and  therefore  the  efficiency  of  the  engine  is 
determined  principally  by  the  vaporizing  point  of  the  lubricat- 
ing oil,  and  consequently  the  higher  the  grade  of  the  oil,  the 
higher  the  allowable  temperature  of  the  cylinder. 

If  cold  water  from  a  hydrant  or  well  be  forced  around  the 
water  jacket  rapidly,  the  power  will  be  greatly  reduced  owing 
to  the  chilling  effect  on  the  expanding  gas.  There  is  not  much 
danger  in  keeping  the  cylinder  of  an  air  cooled  engine  too  cool, 
in  fact  the  great  difficulty  with  this  type  of  engine  is  to  keep  it 
cool  enough  to  prevent  an  excessive  loss  of  lubricating  oil. 

The  valves,  particularly  the  exhaust  valves,  should  be  sur- 
rounded with  sufficient  water  to  keep  them  cool  as  they  are 
subjected  to  more  heat  than  any  other  part  of  the  engine,  and 
are  liable  to  wrap  or  pit.  The  water  leaving  the  jacket  of  a 
gasoline  engine  should  not  exceed  160°  F.,  as  temperatures  in 
excess  of  this  amount  cause  deposits  of  lime  scale. 

When  possible,  a  portion  of  the  cooling  water  should  be  run 
into  the  exhaust  pipe  immediately  after  it  has  completed  its 
flow  around  the  valves  and  cylinders,  as  the  water  cools  the 
gas  so  suddenly  that  the  exhaust  to  atmosphere  is  rendered 
almost  noiseless,  and  the  exhaust  pipe  is  kept  much  cooler  and 

299 


300  GAS,  OIL  AND  STEAM  ENGINES 

less  liable  to  cause  fire  by  coming  into  contact  with  combustible 
objects. 

On  some  engines  the  exhaust  pipe  is  water  jacketed  for 
some  distance  to  prevent  dirty  rusty  pipes  in  the  vicinity  of  the 
efigine  mechanism  and  also  to  prevent  injury  to  the  operator 
should  he  come  into  contact  with  the  pipe. 

Small  engines  and  medium  size  vertical  engines  usually  have 
the  water  jacket  cast  in  one  piece  with  the  cylinder  casting 
and  others  have  a  separate  head  that  is  bolted  to  the  cylinder. 

In  the  latter  type  the  water  flows  from  the  cylinder  to  the 
head  thryugh  ports  or  slots  cut  in  the  end  of  the  cylinder  water 
jacket  that  register  with  similar  slots  in  the  jacket  of  the  head. 

Thus  in  this  construction  we  have  not  only  to  pack  the  joint 
to  prevent  leakage  of  gas  from  the  cylinder,  but  also  to  prevent 
the  leakage  of  cooling  water  from  the  jacket  into  the  cylinder, 
or  outside.  Thus  there  is  always  a  chance  of  water  leaking 
into  the  cylinder  bore  and  causing  trouble  unless  the  packing  is 
very  carefully  installed  and  looked  after. 

In  large  horizontal  engines  the  gas  and  water  joints  are  never 
made  at  the  same  point,  as  it  would  be  practically  impossible 
to  prevent  leakage  into  the  cylinders  of  such  engines. 

When  the  cylinder  and  cylinder  water  jackets  are  cast  in  one 
piece  without  a  water  joint  at  the  junction  of  the  cylinder  and 
the  head,  the  water  connection  between  the  head  and  the  cylinder 
being  made  by  pipes  external  to  the  castings. 

Small,  portable,  stationary  engines  are  sometimes  "HOPPER 
COOLED,"  or  cooled  by  means  of  the  evaporation  of  the 
water  contained  in  an  open  water  jacket  that  surrounds  the 
cylinder. 

The  hopper  is  merely  an  extension  of  the  water  jacket  such 
as  used  on  all  water  cooled  engines,  the  only  difference  being 
that  the  top  of  the  hopper  is  open  permitting  the  free  escape 
of  water  vapor  or  steam  to  the  atmosphere.  The  water  level 
should  be  carried  within  two  inches  from  the  top  of  the  hopper. 

Water  when  converted  into  vapor  or  steam  absorbs  a  great 
quantity  of  heat,  and  of  course  the  steam  carries  the  heat  of 
evaporization  with  it  when  it  escapes  to  the  atmosphere. 

As  the  hopper  is  open  to  the  air,  the  temperature  of  the 
cylinder^cannot  exceed  212°  F.  (temperature  of  boiling  water) 
as  long  as  there  is  sufficient  water  left  to  cover  the  cylinder. 

The  hoppers  contain  sufficient  water  for  runs  of  several  hours' 
duration,  and  as  the  water  boils  away  or  evaporates,  it  may  be 
replenished  by  simply  pouring  more  water  in  the  top  of  the 


GAS,  OIL  AND  STEAM  ENGINES  301 

hopper.  Hopper  cooling  is  used  principally  for  small  portable 
engines  where  the  weight  of  a  water  tank  or  other  cooling 
device  would  be  objectionable  and  also  where  there  is  danger 
of  freezing  the  pipes  and  connections  of  other  systems. 

The  loss  of  water  by  evaporization  is  from  .3  to  .6  of  a  gallon 
per  horsepower  hour;  that  is,  for  a  5  hp.  engine  the  loss  would 
be  from  1.5  to  3  gals,  for  every  hour  that  the  engine  was  oper- 
ated under  full  load. 

Thr  cylinder  and  the  water  jacket  are  cast  in  one  integral 
piece,  with  no  joints  of  any  kind  in  either  the  combustion  cham- 
ber or  in  the  water  jacket. 

A  system  of  cooling  by  which  the  heat  of  the  walls  is  radiated 


Fig.     124.     Air     Cooled     "Grey     Eagle"     Aeronautical     Motor.     Note    the 
Depth    of    Cooling    Ribs. 

to  the  air  directly  without  the  medium  of  water  is  often  used 
on  small  high  speed  engines,  and  is  known  as  "AIR  COOLING." 
This  type  of  cylinder  is  surrounded  with  radiating  ribs  or 
spires  which  increases  the  radiating  surface  of  the  cylinder  to 
the  extent  that  the  required  amount  of  heat  is  lost  to  allow  of 
economical  lubrication.  This  system  is  desirable  where  the 
weight  of  radiators  and  water  would  be  a  drawback,  where  it 
would  be  inconvenient  to  obtain  water,  or  where  there  would 
be  trouble  from  freezing.  An  air  cooled  motor  generally  is 
provided  with  a  fan  that  increases*  the  efficiency  of  the  radiat- 
ing surface  by  changing  the  air  between  the  ribs.  With  aero- 
nautical- motors  such  as  the  Gnome,  and  Gray  Eagle,  shown 
by  Fig.  124,  the  circulation  of  the  air  due  to  the  propeller  and 


302  GAS,  OIL  AND  STEAM  ENGINES 

the  rush  of  the  aeroplane  is  sufficient  to  thoroughly  cool  the 
machine. 

As  a  rule,  the  air  cooled  motor  is  made  more  efficient  in  fuel 
consumption  than  the  water  cooled  type  because  of  the  high 
temperature  of  the  cylinder  walls.  In  fact  all  engines  are  air 
cooled  eventually,  whether  the  heat  is  radiated  at  a  high  tem- 
perature by  the  fires,  .or  at  a  lower  temperature  through  the 
circulating  water  and  radiator. 

When  the  engines  are  of  the  portable  type,  and  likely  to  be 
used  out  of  convenient  reach  of  water,  the  hopper  or  EVAPO- 
RATOR TANK  system  is  used,  the  tank  system  being  used 
for  the  larger  engines.  In  effect,  the  tank  system  is  the  same 
as  the  hopper  cooler,  the  heat  being  dissipated  principally  by 
evaporation,  although  some  heat  is  radiated  from  the  surface 
of  the  tank  itself.  The  difference  between  the  two  systems  is 
merely  one  of  size,  the  tank  offering  a  greater  area  for  the 
emission  of  heat  than  the  hopper. 

A  tank-cooled  engine  has  one  pipe  running  from  the  top  of 
the  cylinder  to  a  point  near  the  top  of  the  tank,  the  bottoms  of 
the  cylinder  and  tank  being  connected  together  by  another  pipe. 

When  the  water  becomes  heated  in  the  cylinder,  it  expands 
and  becomes  lighter  than  the  cold  water  in  the  tank  and  con- 
sequently rises  to  the  surface  of  the  water  in  the  tank  through 
the  upper  pipe.  As  the  warm  water  flows  into  the  tank,  it  is 
immediately  replaced  by  the  heavier  cold  water  that  flows  into 
the  cylinder  from  the  bottom  of  the  tank  through  the  lower 
pipe.  This  successive  discharge  of  the  heated  water  from  the 
cylinder  to  the  tank  sets  up  a  continuous  flow  of  water  through 
the  water  jacket  of  the  cylinder,  which  transfers  the  excess 
heat  of  the  cylinder  to  the  tank  where  it  is  dissipated  to  the 
atmosphere  by  evaporation  and  radiation. 

The  circulation  of  the  cooling  water  set  up  by  the  action  of 
heat  or  the  expansion  of  the  water  is  called  Natural  or  Thermo 
Syphon  circulation. 

Cooling  tanks  may  be  used  profitably  with  stationary  en- 
gines if  the  tank  can  be  located  so  that  vapor  and  steam  pro- 
duced will  not  be  objectionable.  If  the  tank  is  used  inside  of 
a  building,  the  vapor  should  be  conveyed  to  the  outside  air  by 
means  of  a  stack  or  chimney,  or  by  means  of  a  small  ventilating 
fan  driven  by  the  engine. 

The  water  consumption  of  a  cooling  tank  is  from  .3  to  .6 
gallons  per  hour,  the  exact  quantity  varying  with  the  atmos- 
pheric conditions  and  temperature, 


GAS,  OIL  AND  STEAM  ENGINES 


303 


For  engines  of  from  10  to  50  horsepower  a  battery  of  cooling 
tanks  may  be  used,  the  number  depending  on  the  size  of  the 
engine.  To  maintain  the  proper  temperature  under  varying 
loads,  one  or  more  tanks  may  be  cut  out  of  service  when  the 


Hall-Scott   Aeroplane   Motor   Mounted    in    Martin   Biplane.      Radiator    Shown 
Above   Motor  and  in   Front   of  Top   Wing. 


load  is  changed.  For  natural  circulation,  the  tank  should  be 
installed  so  that  the  bottom  of  the  tank  is  above  the  bottom 
of  the  cylinder.  If  placed  much  lower  a  pump  should  be  used. 


304  GAS,  OIL  AND  STEAM  ENGINES 

If  water  is  used  from  the  city  mains  from  10  to  15  gallons 
will  be  required  per  horsepower  hour,  the  exact  quantity  varies 
with  the  temperature  of  the  supply. 

The  water  from  very  large  stationary  engines  is  cooled  by 
allowing  it  to  trickle  down  through  a  cooling  tower,  which  is 
built  somewhat  like  the  screen  cooler  only  on  a  larger  scale, 
built  somewhat  like  the  screen  cooler  only  on  a  larger  scale. 
The  object  of  the  cooling  tower  is  to  present  the  greatest  pos- 
sible surface  of  water  to  the  air,  this  is  accomplished  by  screens 
or  baffles  that  turn  the  water  over  and  over  as  it  falls.  The 
water,  well  cooled,  finally  collects  in  a  cistern  at  the  base  of 
the  tower  from  which  it  is  pumped  back  to  the  engine  and  thus 
is  used  over  and  over  again.  This  is  an  ideal  system  when 
water  is  expensive  and  when  engines  of  considerable  power  are 
used. 

(126)  Cooling  System  Troubles. 

Overheating  caused  by  deposits  of  scale  or  lime  in  the  jacket 
is  one  of  the  most  common  causes  of  an  excessively  hot  cyl- 
inder. When  hard  water  containing  much  lime  is  heated,  the 
lime  is  .deposited  as  a  solid  on  the  walls  of  the  vessel  forming 
a  hard,  dense,  non-conducting  sheet.  When  scale  is  deposited 
on  the  outside  of  the  cylinder  walls  it  prevents  the  transfer  of 
the  heat  from  the  cylinder  to  the  cooling  water  and  consequently 
is  the  cause  of  the  cylinder  overheating.  Besides  acting  as  an 
insulator  or  heat,  the  deposit  also  causes  trouble  by  obstructing 
the  pipes  and  water  passages,  diminishing  the  water  supply  and 
aggravating  the  trouble. 

Scale  interferes  with  the  action  of  the  thermo  syphon  system 
more  than  with  a  pump,  as  the  pressure  tending  to  circulate  the 
water  is  much  lower.  Whatever  system  is  used,  the  scale  should 
be  removed  as  often  as  possible,  the  number  of  removals  de- 
pending, of  course,  on  the  "hardness"  of  the  water. 

Large  horizontal  engines  are  usually  provided  with  hand  holes 
in  the  jacket,  th'rough  which  access  may  be  had  to  the  interior 
surfaces  on  which  the  scale  collects.  Under  these  conditions  the 
scale  may  be  removed  by  means  of  a  hammer  and  chisel. 

The  scale  may  be  softened  by  empt3nng  half  the  water  from 
the  jacket  and  pouring  in  a  quantity  of  kerosene  oil,  the  inlet 
and  outlet  pipes  being  stopped  to  prevent  the  escape  of  the  oil. 
The  engine  should  now  be  started  and  run  for  a  few  minutes 


GAS,  OIL  AND  STEAM  ENGINES  305 

with  the  mixture  of  kerosene  and  water  in  the  jacket;  no  fresh 
water  being  admitted  during  this  time.  After  the  mixture  has 
become  boiling  hot,  stop  the  engine  and  allow  it  to  cool;  it 
will  be  found  that  the  scale  has  softened  to  the  consistency  of 
mud,  and  may  easily  be  washed  out  of  the  jacket. 

The  work  of  removing  the  scale  can  be  reduced  to  a  minimum 
by  filling  the  jacket  with  a  solution  of  1  part  of  Sulphuric  Acid 
and  10  parts  of  water,  allowing  it  to  stand  over  night.  The  scale 
will  be  precipitated  to  the  bottom  of  the  jacket  in  the  form  of 
a  fine  powder  and  may  be  easily  washed  out  in  the  morning. 

If  the  jacket  water  is  kept  at  a  temperature  above  185°  F. 
the  amount  of  scale  deposited  will  be  nearly  doubled  over  that 
deposited  at  160°  F. 

Wash  out  sand  and  dirt  occasionally,  a  strainer  located  in  the 
pump  line  will  help  to  keep  the  jacket  clear  and  free  from  for- 
eign matter. 

If  a  solution  of  carbonate  of  soda,  or  lye,  and  water  are  al- 
lowed to  stand  in  the  cylinder  over  night,  the  deposit  will  be 
softened  and  the  work  with  the  chisel  will  be  made  much  easier. 

If  a  radiator  is  used  (automobile  or  aero  engine)  the  deposit 
can  be  removed  with  soda,  never  use  acid,  lye,  or  kerosene  in 
a  radiator  or.  with  an  engine  with  a  sheet  metal  water  jacket. 

Obstructions  in  Water  Pipes.  Poor  water  circulation  may  be 
caused  by  sand,  particles  of  scale,  etc.,  clogging  the  water  pipes, 
or  by  the  deterioration  of  the  inner  walls  of  the  rubber  hose 
connections.  Sometimes  a  layer  of  the  rubber,  or  fabric  of  the 
hose  may  loosen  from  the  rest  and  the  ragged  end  may  obstruct 
the  passage. 

A  sharp  bend  in  a  rubber  hose  may  result  in  a  "kink"  and  en- 
tirely close  the  opening. 

The  packing  in  a  joint  may  swell,  or  a  washer  may  not  have 
the  opening  cut  large  enough,  either  case  will  result  in  a  poor 
circulation. 

Sediment  is  particularly  liable  to  collect  or  form  in  a  pocket, 
pipe  elbow,  or  in  the  jacket  opposite  the  pipe  opening.  Oil 
should  be  kept  off  of  rubber  hose  connections  as  it  will  cause 
them  to  deteriorate  rapidly,  this  may  finally  result  in  water 
circulation  troubles.  Rubber  pipe  joints  between  the  engine  and 
the  radiator  or  tanks  are  advisable  as  they  do  not  transmit  the 
vibration  of  the  engine,  and  hence  reduce  the  strain  on  the 
piping.  A  strainer  should  be  provided  in  order  to  reduce  the 
amount  of  foreign  material  in  the  water. 

Radiators.     A    clogged    radiator   will    give    the    same    results 


306  GAS,  OIL  AND  STEAM  ENGINES 

as  a  clogged  jacket  with  the  exception  that  steam  will  issue  from 
the  radiator  if  the  circulation  is  not  perfect. 

If  the  radiator  becomes  warm  over  its  entire  surface  it  is 
evident  that  the  water  is  circulating,  the  temperature  being  a 
rough  index  of  the  freedom  of  the  water,  or  the  interior  con- 
dition of  the  surfaces.  A  leaking  radiator  may  be  temporarily 
repaired  with  a  piece  of  chewing  gum. 

Should  the  radiator  be  hot  and  steaming  at  the  top  and  remain 
cold  at  the  bottom  for  a  time,  it  shows  that  the  water  is  not 
circulating  and  that  the  jackets  on  the  cylinders  are  full  of 
steam.  Such  a  condition  usually  is  indicative  of  clogging  be- 


Natural    Gas    Plant   at    Independence,    Kansas,    Used    for    Pumping   Gas    From 
the   Wells  to   Various   Distributing   Points. 

tween  the  bottom  of  the  radiator  and  pump,  between  the  pump 
and  bottom  of  cylinders,  or  of  a  defective  pump. 

Thermo-syphon  radiators  are  more  susceptible  to  the  effects 
of  sediment  and  clogging  than  those  circulated  by  pumps. 

A  radiator  may  fail  to  cool  an  engine  because  of  a  slipping 
or  broken  belt  driving  the  fan,  or  on  account  of  a  loose  pulley 
or  defective  belt  tension  adjuster.  Keep  the  belt  tight.  The 
fan  may  stick  on  account  of  defective  bearings. 

Radiator  may  be  AIR  BOUND,  due  to  pockets  or  bends  in 
the  piping  holding  the  air. 

Rotary  Pump  Defects.  A  defective  circulating  pump  will 
cause  overheating,  as  it  will  supply  little  if  any  water  to  the 
jackets. 


GAS,  OIL  AND  STEAM  ENGINES  307 

Examine  the  clutch  or  coupling  that  drives  the  pump  and  see 
that  the  key  or  pin  that  fastens  it  to  the  shaft  is  in  place. 
Next  see  that  the  driving  pinion  and  gear  are  in  mesh  and 
properly  keyed  to  their  respective  shafts. 

In  some  cases  the  shaft  has  been  twisted  off,  or  the  coupling 
pin  sheared  through  by  reason  of  the  shaft  rusting  to  the  pump 
casing.  Worn  gears  or  impellers  IN  THE  PUMP  reduce  the 
output  and  cause  heating,  as  will  a  sheared  driving  pin  in  the 
impeller.  Wear  and  bad  impeller  fits  reduce  the  capacity  of 
the  pump. 

Scale  or  sediment  collecting  in  the  pump  sometimes  strips 
the  pins  or  impeller  teeth.  Note  the  condition  of  the  gaskets 
or  whether  the  pump  shaft  is  receiving  the  proper  amount  of 
grease.  Put  a  strainer  in  pump  intake.  See  that  no  leak  occurs 
on  pump  intake  pipe. 

To  avoid  the  trouble  and  expense  due  to  cracked  water 
jackets,  never  neglect  to  drain  the  cylinders  and  piping  from 
all  water  in  freezing  weather.  Drain  cocks  should  be  provided 
at  the  lowest  points  in  the  water  circulating  system  for  this 
purpose.  It  would  be  well  to  provide  an  air  cock  at  the  highest 
point  in  the  line  in  order  that  all  of  the  water  can  drain  out 
as  soon  as  the  drain  cock  is  opened. 

With  automobile  or  portable  engines  it  is  not  always  con- 
venient or  possible  to  drain  the  engine  every  time  that  it  is 
stopped  and  consequently  we  must  resort  to  a  "non-freezing" 
mixture  or  at  least  a  solution  that  will  not  solidify  under  ordi- 
nary winter  temperatures.  Such  a  solution  should  be  chosen 
with  care,  as  many  will  cause  the  corrosion  and  destruction  of 
the  jackets  and  piping;  NEVER  USE  COMMON  SALT  and 
water  under  any  conditions. 

Wood  alcqhol  and  water  in  equal  parts,  is  often  used  for 
automobiles,  but  is  rather  expensive  for  portable  engines  hav- 
ing a  comparatively  great  amount  of  water  in  circulation. 

Unless  the  circulating  system  is  absolutely  air  tight,  as  it  is 
when  radiators  are  used,  alcohol  will  be  lost  by  evaporation 
and  must  be  replaced  frequently. 

The  most  practical  solution  for  the  average  engine  used, 
is  made  up  by  dissolving  about  five  pounds  of  CALCIUM 
CHLORIDE  in  one  gallon  of  water.  This  mixture  will  stand 
a  temperature  of  about  15°  F  below  zero,  and  if  diluted  to  half 
the  strength  will  not  freeze  above  zero. 

Use  CALCIUM  CHLORIDE,  not  ordinary  Salt  (Sodium 
Chloride). 


CHAPTER  XII 
GOVERNORS  AND  VALVE  GEAR 

(127}  Hit  and  Miss  Governing. 

When  the  speed  of  an  engine  is  held  constant  for  varying 
loads  by  missing  explosions  on  the  light  loads  and  increasing 
the  number  for  heavy  loads,  the  governing  system  is  said  to  be 
of  the  "hit  and  miss  type."  The  mixture  remains  constant  in 
quantity  and  quality  in  this  type  of  engine.  A  hit  and  miss 
governor  allows  only  enough  charges  to  be  fired  to  keep  the 
speed  constant. 

When  the  load  falls  off,  with  a  natural1  tendency  on  the  part 
of  the  engine  to  increase  its  speed,  the  governor  cuts  out  the 
next  explosion  by  holding  the  exhaust  valve  open  and  the  inlet 
closed,  thus  preventing  fresh  mixture  from  being  drawn  into 
the  cylinder.  With  an  increase  in  load,  the  governor  allows 
the  valves  to  follow  their  regular  cycle  with  the  result  that  a 
greater  or  less  number  are  fired  in  succession.  Hit  and  miss 
governing  is  very  economical  for  only  full  charges  of  the  most 
perfect  mixture  are  fired,  and  with  short  exhaust  pipes  the 
scavenging  is  much  better  than  with  other  forms  of  governing. 
The  principal  difficulty  with  this  system  is  that  the  regulation 
is  not  as  perfect  as  with  some  other  types. 

(128)  The  Throttling  System. 

Unlike  the  hit  and  miss  system  of  governing,  the  throttling 
type  of  governor  allows  the  engine  to  take  an  explosion  on 
every  working  stroke,  the  speed  being  held  constant  by  either 
regulating  the  quality  or  quantity  of  the  mixture,  or  both. 
Throttle  governor  permits  of  close  speed  regulation  as  the  im- 
pulses are  more  frequent  and  not  so  violent  as  with  the  hit  and 
miss  system. 

The  governor  acts  directly  on  the  throttle  valve,  and  at  no 
time  is  the  operating  mechanism  disengaged  from  the  driving 
cam.  The  throttle  governor  engine  is  particularly  well  adapted 
'for  driving  dynamos,  supply  electric  light,  as  the  uniform  speed 

308 


GAS,  OIL  AND  STEAM  ENGINES  309 

gives  a  smooth,  steady  light  without  the  objectionable  flickering 
so  likely  with  the  hit  and  miss  engine.  To  obtain  the  best  fuel 
economy  with  a  throttling  engine,  it  should  be  run  close  to  its 
rated  capacity,  as  the  poor  and  imperfect  mixture  admitted  at 
light  loads  considerably  increases  the  fuel  consumption. 

Practically  all  motors  of  the  variable  speed  type  such  as  are 
used  on  automobiles  and  motor  boats  are  controlled  manually 
by  the  throttle;  although  marine  motors  are  often  fitted  with 


Fig.   76-d.     De   La   Vergne   Governor. 

governors   to   prevent    racing  when   the   screw   is   lifted   out   of 
the  water  in  a  heavy  sea. 

(129)  The  Controlling  Governor. 

The  governor  proper  depends  upon  centrifugal  force  for  its 
action,  and  generally  consists  of  two  weights  which  are  pivoted 
at  one  end  to  a  rotating  shaft  driven  by  the  engine.  When 
these  weights  are  rotated  rapidly  the  bottoms  are  thrown  out- 
wardly by  the  centrifugal  force  and  tend  to  assume  a  horizontal 
position.  The  faster  the  weights  are  rotated,  the  greater  will 
be  the  tendency  for  the  bottoms  of  the  weights  to  come  into 
the  horizontal,  and  the  greater  will  be  the  pressure  exerted  by 
them  on  the  controlling  levers  connected  to  the  throttle.  It  is 
evident  that  the  centrifugal  pull  on  the  weights  varies' directly 


310 


GAS,  OIL  AND  STEAM  ENGINES 


Fig.     124-d.      Governor     and     Governor     Mechanism     of     Fairbanks-Morse 
Type  "R  E"  Engine.     The  Fly-Balls,   Springs,  and  Control  Rods  Are 
Shown  on  the  Governor  Staff.     The  Upper  End  of  the  Bell  Crank 
Goes  to  the  Throttle. 

with  the  speed  of  rotation  and  consequently  with  the  speed  of 
the  engine.  The  exact  relation  between  the  travel  of  the  weights 
and  the  speed  of  the  engine  is  controlled  by  a  spring  that  acts 
between  arms  cast  on  the  weights  and  the  spindle.  If  a  heavy 
spring  is  used,  greater  speed  must  be  attained  to  move  the 
weights  a  given  distance  than  with  a  weak  spring,  as  the  centri- 
fugal force  must  be  greater. 


GAS,  OIL  AND  STEAM  ENGINES  311 

The  throttle  valve  of  the  engine  is  connected  by  a  rod  to  the 
governor  through  a  sliding  collar  in  such  a  way  that  the  move- 
ment of  the  governor  weights  due  to  an  INCREASE  of  speed 
partially  closes  the  valve  until  the  speed  of  the  engine  is  re- 
duced. Should  the  speed  of  the  engines  DECREASE,  owing  to 
a  heavy  load  coming  on,  the  spring  will  force  the  balls  to  occupy 
a  lower  position  which  will  increase  the  valve  opening  until  the 
engine  again  reaches  the  normal  speed  for  which  the  tension 
of  the  spring  is  adjusted. 

Thus  the  speed  of  the  engine  is  kept  practically  constant  by 
the  action  of  the  governor  in  opening  and  closing  the  throttle, 
which  in  turn,  varies  the  QUANTITY  of  mixture  admitted  to 
the  cylinder.  The  QUALITY  of  the  mixture  is  varied  by  hand, 
in  the  engine  by  means  of  cocks  in  both  the  air  and  gas  pipes. 
The  GOVERNOR  PROPER  is  of  practically  the  same  con- 
struction in  the  hit  and  miss  engine,  the  difference  of  the  two 
'types  lying  in  the  method  of  connecting  it  to  the  controlling 
system.  In  one  case  (hit  and  miss)  the  governor  controls  the 
exhaust  valve,  and  in  the  other  (throttling)  it  controls  the  quan- 
tity of  gas  admitted  by  the  throttle  valve.  The  speed  of  the 
engine  may  be  varied  within  certain  limits  by  a  lever  connected 
to  the  valve  controlling  rod. 

(130)  Types  of  Governors. 

The  types  of  governors  used  o-n  the  leading  makes  of  en- 
gines will  be  found  described  and  illustrated  in  Chapter  V  which 
treats  of  each  engine  in  detail. 

(131)  Governor  Troubles. 

Hit  and  miss  governor  troubles  may  be  due  to  the  following 
defects: 

BINDING  GOVERNOR  COLLAR,  stuck  with  dirt  or  gummy 
oil,  will  cause  the  engine  to  die  under  load,  and  overspeed  on 
light  load. 

INLET  VALVE  LOCK  may  be  worn  in  such  a  manner  as 
to  prevent  the  valve  from  seating  during  the  idle  strokes  and 
lose  fuel,  or  cause  overspeeding. 

DETENT  LEVER  KNIFE  EDGE  may  be  worn,  or  rounded 
off,  so  that  the  exhaust  valve  is  not  held  open  for  the  idle 
stroke.  This  defect  will  cause  overspeeding. 

SPEED  CHANGING  LEVER  may  work  loose  and  cause  the 
speed  to  vary  erratically. 

GOVERNOR  WEIGHTS  may  be  stuck  on  pins  with  dirt 
or  gummy  oil  causing  engine  to  overspeed. 


312  GAS,  OIL  AND  STEAM  ENGINES 

LOST  MOTION  IN  GOVERNOR  GEAR  such  as  loose  pins 
and  bushings,  worn  rollers,  or  bearing  surfaces  will  cause  the 
speed  to  vary  continuously.  LOST  MOTION  on  portable  en- 
gines will  cause  the  engine  to  run  normally  in  one  position, 
and  overspeed  in  another. 

WEAK  OR  BROKEN  SPRINGS  ON  GOVERNOR  will 
cause  engine  to  lose  speed  or  die  down  altogether.  Springs 
may  be  stiffened  by  pulling  out  the  coils. 

DRY  GOVERNOR  BEARINGS  or  joints  will  cause  binding 
and  cause  governor  to  act  sluggishly.  Use  plenty  of  lubricant. 

WORN  ROLLERS  may  cause  a  speed  variation.  Keep  the 
governor  well  oiled,  clean,  and  free  from  gum. 

If  the  knife  edges  are  allowed  to  slip  over  one  another,  much 
wear  is  caused  on  the  cams  and  if  allowed  to  continue,  sooner 
or  later  the  engine  will  run  away.  Springs  will  weaken  with 
age  and  hard  usage.  With  belt  driven  governors  see  that  the 
belt  is  tight  and  that  the  lacing  is  in  good  condition  for  a  slack 
belt  may  allow  the  engine  to  overspeed. 

I  advise  that  every  purchaser  of  an  agricultural  motor  read 
his  instruction  book  with  care,  that  is,  locate  all  oil  holes  and 
note  the  action  and  purpose  of  every  part.  If  in  doubt  as  to 
any  part  of  its  use  write  the  manufacturer  of  the  motor. 

(132)  Throttling  Governor  Troubles. 

STICKING  GOVERNOR  VALVE  will  cause  the  engine  to 
overspeed;  remove  the  gum  and  dirt. 

LOOSE  PINS  OR  BUSHINGS,  or  lost  motion  in  any  part 
of  the  governor  mechanism  will  cause  irregular  motion  or  run- 
ning; be  sure  that  the  bearings  and  joints  are  well  oiled. 

STUCK  PINS  will  cause  the  engine  to  overspeed  on  light 
loads,  and  fall  down  on  the  normal  load,  or  cause  racing. 

WEAK  OR  BROKEN  SPRINGS  will  cause  the  engine  to 
lose  speed  or  to  lie  down  altogether  even  on  light  loads. 

STIFF  GOVERNOR  SPRINGS  cause  the  engine  to  speed  up. 

SLIDING  COLLAR  stuck  will  cause  racing  or  a  fluctuation 
in  the  speed.  Keep  the  governor  well  oiled,  clean,  and  free 
from  gum. 

The  governing  valve  should  be  removed  from  its  care  fre- 
quently and  thoroughly  cleaned  with  kerosene.  Deposits  of 
carbon  and  gummed  oil  at  this  point  are  dangerous  because  of 
the  likelihood  of  their  causing  overspeeding. 

(133)  Valve  Gear  Arrangement. 

The  valve  operating  mechanism  lay-out  depends  upon  the  cyl- 


GAS,  OIL  AND  STEAM  ENGINES 


313 


inder  and  valve  arrangement,  and  consequently  varies  in  detail 
with  different  engines. 

Fig.  F-14-15  in  Chapter  V,  shows  the  valve  gear  of  an  upright 
engine    having    the    inlet    and    the    exhaust    valves    located    in 


pockets  placed  at  one  side  of  the  cylinder.  The  inlet  valve  is 
operated  by  a  valve  rod  that  is  actuated  by  the  cam.  The  ex- 
haust valve  stem  is  raised  and  lowered,  directly,  through  a  cam 
on  the  same  shaft.  The  method  of  driving  the  valves  in  this 


314  GAS,  OIL  AND  STEAM  ENGINES 

engine  is  practically  standard  for  all  vertical  engines  having  the 
valves  located  in  pockets.  This  system  is  used  in  a  greater 
proportion  of  automobile  engines. 

The  opposed  engine  has  the  cylinders  arranged  on  opposite 
side  of  the  crank  case,  and  makes  an  exceedingly  well  balanced 
and  quiet  running  engine;  as  there  is  no  point  in  the  revolution 
where  either  the  crank  throws  or  connecting  rods  have  an  un- 
equal angularity,  or  differ  in  velocity. 

While  this  type  of  two  cylinder  engine  is  common  in  automo- 
bile practice,  it  is  not  often  met  with  in  stationary  work,  the 
cam-box  and  the  cam  being  directly  in  the  center  of  the  crank 
case. 

The  opposed  type  of  engine  is  particularly  well  adapted  for 
aeroplane  service  as  a  steady,  quiet  running  engine  is  an  absolute 
necessity  because  of  the  frail  construction  of  the  aeroplane 
frame. 

(134)  Cam  Shaft  Speeds. 

The  valves  of  the  gas  engine  are  opened  and  closed  by  means 
of  cams  or  eccentrics,  that  are  geared  to  the  crankshaft,  and 
which  also  control  the  timing. 

As  a  four  stroke  cycle  engine  performs  all  of  the  events,  or 
a  complete  cycle  in  two  revolutions  of  the  crankshaft,  it  is 
evident  that  the  cam  must  go  through  the  routine  in  one  revolu- 
tion or  must  revolve  at  ONE-HALF  OF  THE  CRANKSHAFT 
SPEED. 

Therefore  the  cam  gear  ratio  must  be  as  one  is  to  two,  the 
smaller  gear  being  placed  on  the  crankshaft,  the  gears  being 
known  as  the  "half  time  gears." 

As  a  two  stroke  cycle  engine  goes  through  the  routine  of 
events  in  every  revolution,  the  cam-shaft  must  run  at  crank- 
shaft speed  so  that  the  cam  out-line  makes  one  revolution  in 
the  same  time  as  the  crank.  The  cam  shaft  speeds  given  here 
apply  to  all  engines  of  the  corresponding  cycle  no  matter 
whether  the  valves  are  of  the  poppet,  rotary  or  slide-sleeve 
types. 

(135)  Valve  Gear  Troubles. 

The  valve  gear  mechanism  causes  trouble  principally  through 
the  wear  of  the  various  parts  which  results  in  a  change  in  the 
valve  timing,  or  in  the  lift  of  the  valves.  Loss  of  power,  MIS- 
FIRING, and  overheating  are  the  result  of  such  derangements. 

Often  trouble  is  caused  in  reassembling  the  valve  mechanism 


GAS,  OIL  AND  STEAM  ENGINES  315 

after  the  engine  has  been  torn  down  for  repairs,  which  trouble 
may  generally  be  traced  to  incorrect  gear  meshing. 

The  following  list  will  give  the  principal  defects  due  to  the 
wear  of  the  valve  mechanism. 

(a)  WORN  CAM  GEARS  change  timing  because  of  play,  or 
"back  lash"  in  the  teeth,  or  cause  a  howling  or  grinding  noise, 
that  will  cause  the  owner  to  believe  that  the  end  of  the  engine 
is  near.     MISFIRING  and  LOSS  of  power  are  probable  results 
of  a  change  in  the  timing.     If  any  of  the  teeth  are  stripped  from 
the  gear  you  may  be  sure  that  the  timing  is  changed.     Replace- 
ment with  a  new  gear  is  the  only  cure  for  a  worn  or  broken 
gear. 

(b)  GEARS  NOT  IN  PROPER  MESH  due  to  an  error  in 
assembling  the  gears,  will  prevent  the  engine  from  being  started, 
or  cause  misfiring  and  loss  of  power. 

The  maker  of  the  engine  generally  marks  the  teeth  that  go 
together,  but  if  no  such  marks  appear,  the  owner  should  center 
punch  or  scratch  them  before  taking  down  the  engine. 

(c)  A  GEAR  SLIPPING  ON  THE  SHAFT,  due  to  a  mis- 
sing key  in  the  gear,  or  to  a  loose  set-screw  will  cause  all  of 
the  troubles  due  to  a  change  in  the  timing.     Examine  the  key 
carefully,  for  dirt  often  collects  in  the  key-way  to  such  an  ex- 
tent that  it  is  liable  to  be  mistaken  for  the  key.     Keys  and  pins 
have  sheared  in  two,  allowing  the  shaft  to  slip  in  the  gear. 

(d)  WORN   CAM-SHAFT   BEARINGS   are   the   cause   of 
trouble,   as   they  will  change  both   the   timing  and   the  lift  of 
the  valves.     If  much  play  exists  in  the  bearing,  it  will  prevent 
the  valves  from  lifting  at  the  proper  time,  and  will  also  reduce 
the  lift  by  the  amount  of  the  play,  which  sometimes  has  a  con- 
siderable effect  on  the  free  passage  of  the  gases.     If  the  cam- 
shaft bearings  are  of  the  bushing  type  they  should  be  replaced 
with  new  paying  attention  at  the  same  time  to  the  condition  of 
the  shaft.     If  rough  or  shouldered  the  shaft  should  be  machined 
to  a  dead  smooth  surface.     If  on  a  large  engine  and  of  the  ad- 
justable type,  the  shims  should  be  removed  as  required  or  the 
wedges  adjusted. 

(e)  LOOSE  CAMS  OR  ECCENTRICS  will  change  the  tim- 
ing because  of  lost  or  sheared  keys.     If  your  cams  are  not  in- 
tegral with  the  shaft,  look  them  over  occasionally  and  be  sure 
that  the  keys  are  tight.    Loose  cams  will  produce  thumping  and 
grinding  and  may  often  be  located  by  the  sound.     See  that  the 
key-way  is  not  worn  when  fitting  keys. 

If  the  cams  are  fitted  with  taper  pins  it  would  be  well  to  ream 


316  GAS,  OIL  AND  STEAM  ENGINES 

the  hole  before  placing  new  pins,  as  there  is  a  liability  of  the 
hole  being  worn  oval. 

(f)  A  TWISTED  OR  SPRUNG  CAM-SHAFT  will  change 
the  positions  of  the  cams  relative  to  one  another,  and  not  only 
will  change  the  time  of  all  cylinders,  but  will  change  their  time 
relatively  causing  the  engine  to  run  out  of  balance,  or  produce 
an  unusual  vibration. 

(g)  WORN  CAMS  are  causes  of  a  change  of  timing  on  all 
types  of  engines,  and  are  the  most  frequent  cause  of  reduced 
valve  lift  with  its  consequent  trouble  of  overheating. 

If  the  outline  or  contour  of  a  cam  is  changed  with  wear  it 
should  be  replaced,  if  keyed  to  the  shaft,  as  it  will  be  a  constant 
source  of  trouble.  If  the  cams  and  cam-shaft  are  in  one  integral 
piece,  it  will  be  necessary  to  replace  the  entire  shaft. 

(h)  WORN  CAM  ROLLERS  AND  ROLLER  PINS  will 
reduce  the  lift  of  the  valves,  and  in  the  case  of  a  broken  or 
sheared  pin  will  prevent  the  valve  from  lifting  at  all.  Always 
replace  loose  pins  or  loose  rattling  roller. 

(i)  PUSH  ROD  DEFECTS.  Too  much  clearance  between 
the  push  rod  and  valve  stem  will  reduce  the  lift  of  the  valves  and 
change  the  timing.  The  clearance  for  small  engines  should  be 
equal  to  the  thickness  of  a  visiting  card,  and  for  large  engines 
is  somewhat  larger,  say  1-16".  The  increase  of  clearance  is  due 
principally  to  wear. 

Too  small  a  clearance  should  be  avoided  for  the  reason  that 
the  valve  stems  expand  with  the  heat  and  will  lift  the  valves  too 
soon,  or  even  permanently  until  readjusted.  Broken  valve  springs 
will  cause  trouble,  or  lost  keys  that  retain  the  valve  spring 
washers.  Loose  adjusting  screws  on  the  push  rods  or  stripped 
threads  will  delay  the  valve  opening. 

(j)  TAPPET  LEVER  DEFECTS  are  generally  caused  by 
wear  or  poor  adjustment.  Loose  pins  or  bushings,  too  much 
clearance  between  the  tappet  and  valve  stem  or  broken  valve 
springs,  or  loose  adjusting  screws  will  produce  changes  in  the 
timing  or  valve  lift 

(k)  BENT  VALVE  ROD.  A  bent  valve  rod  will  shorten 
the  travel  of  the  valves,  and  change  the  timing. 

(1)  CAM  LEVER  OR  PIN  will  cause  timing  troubles  if  the 
pin  or  bushing  are  loose  or  worn,  by  reducing  the  travel  of 
the  valves. 

When  occasion  arises  for  the  removal  of  valves,  the  oppor- 
tunity should  be  taken  to  clean  the  stems  and  guides,  which 
may  be  more  or  less  gummed  with  ancient  oil.  Freedom  of 


GAS,  OIL  AND  STEAM  ENGINES  317 

valve  movement  is  of  extreme  importance,  and  for  this  reason 
neither  the  cleaning  nor  the  lubrication  of  the  stems  and  guides 
should  be  neglected.  The  occasional  use  of  a  little  kerosene 
will  prevent  gummy  accumulations,  but  care  should  be  taken 
not  to  allow  the  kerosene  to  wash  out  all  of  the  oil  and  thereby 
leave  the  surfaces  dry. 

A  broken  valve  spring,  though  not  a  common  occurrence,  is 
not  an  unknown  possibility.  If  no  spare  spring  is  at  hand,  a 
plan  that  can  be  recommended  is  to  turn  the  broken  spring  end 
for  end,  thus  bringing  the  finished  ends  up  together;  this  will 
prevent  the  spring  from  shortening  by  overlapping,  and  wind- 
ing itself  together. 

(136)  Valve  Timing. 

The  exact  time  at  which  the  valves  of  a  four  stroke  cycle 
engine  open  and  close  depends  to  a  great  extent  upon  the  speed 
of  the  engine,  the  fuel  used,  the  compression  pressure,  and  the 
relation  of  the  bore  to  the  stroke. 

As  these  items  vary  in  nearly  every  make  of  engine  there 
has  appeared  in  the  technical  press,  a  great  mass  of  seemingly 
conflicting  data.  Engine  speed  is  the  principal  factor  in  de- 
termining the  timing. 

Correct  valve  timing  plays  a  considerable  part  in  the  output 
and  efficiency  of  an  engine,  for  if  the  inlet  valve,  for  example, 
opens  too  late,  the  cylinder  will  not  receive  a  full  charge.  If 
it  opens  too  early  the  hot  gases  in  the  cylinder  will  ignite  the 
gas  in  the  carburetor  and  cause  back-firing.  Should  the  ex- 
haust open  too  late,  the  retention  of  the  hot  gas  in  the  cylinder 
is  likely  to  cause  overheating. 

The  timing  of  the  valves  is  usually  expressed  in  degrees  of 
the  circle  described  by  the  crank-pin,  or  the  angle  formed  by 
the  crank  with  the  center  line  of  the  cylinder  at  the  time  the 
valve  is  to  open  or  close. 

(137)  Valve  Setting  on  Stationary  Engines. 

The  exhaust  should  open  when  the  crank  lacks  30°  of  com- 
pleting the  outer  end  of  the  power  stroke,  that  is,  the  crank 
should  make  an  angle  of  30°  with  the  center  line  of  the  cylinder 
when  the  exhaust  valve  begins  to  open,  and  should  be  inclined 
AWAY  from  the  cylinder.  Some  makers  have  the  exhaust  open 
a  little  later  in  the  stroke,  but  little  is  to  be  gained  with  a  later 
opening  as  the  retention  of  the  charge  beyond  30°  heats  the 
cylinder  and  does  very  little  towards  developing  power.  The 


318  GAS,  OIL  AND  STEAM  ENGINES 

only  advantage  of  the  late  opening  is  that  the  valve  opens  against 
a  lower  pressure  and  causes  slightly  less  wear  on  the  parts. 

The  exhaust  valve  should  close  5°  AFTER  the  crank  has 
passed  the  INNER  dead  center  on  the  exhaust  or  scavenging 
stroke,  although  some  makers  close  the  valve  exactly  on  the 
dead  center.  The  5°  should  be  given  to  allow  the  gas  all  possible 
chance  of  escape.  The  piston  is  said  to  be  on  the  inner  dead 
center  when  it  is  in  the  cylinder  as  far  as  it  will  go,  and  on 
the  outer  dead  center  when  it  is  on  the  center  nearest  the  crank- 
shaft. 

The  INTAKE  valve  should  open  about  5°  AFTER  the  exhaust 
valve  closes,  or  10°  after  the  crank  passes  the  inner  dead  center. 
The  inlet  valve  should  NEVER  open  before  the  exhaust  valve 
closes  on  a  low  speed  engine.  The  above  timing  is  for  engines 
running  150-600  R.P.M.  The  automatic  type  of  inlet  valve,  of 
course,  cannot  be  timed,  but  attention  should  be  paid  to  the 
strength  and  tension  of  the  spring  and  the  condition  of  the  valve 
stem  guides. 

The  inlet  valve  should  close  10°  AFTER  the  crank  passes  the 
outer  dead  center  in  order  that  the  cylinder  be  filled  to  the  full- 
est possible  extent."  If  the  valve  closed  exactly  on  the  dead 
center  a  partial  vacuum  will  exist  and  the  charge  retained  in 
the  cylinder  will  be  comparatively  small,  but  if  the  valve  re- 
mains open  past  this  point  the  air  would  have  time  to  completely 
fill  the  cylinder  and  develop  the  capacity  of  the  engine.  The 
longer  the  inlet  pipe,  the  longer  the  inlet  valve  opening. 

(138)  High  Speed  Engine  Valve  Timing. 

The  faster  a  motor  turns,  all  other  things  being  equal,  the 
greater  the  amount  of  advance  necessary  with  the  valves,  as  the 
higher  the  speed  the  less  the  time  required  to  fill  or  empty  the 
cylinder.  In  a  short  stroke  high  speed  motor  the  exhaust  should 
close  and  the  intake  open  as  early  as  possible  in  order  to  admit 
the  full  charge.  The  exhaust  should  open  early  to  allow  of  the 
full  escape  of  the  gases,  as  the  time  allowed  for  expulsion  is  ex- 
tremely short  when  an  engine  runs  1,000  R.P.M.  and  the  back 
pressure  is  liable  to  be  considerable. 

The  inlet  valve  of  high  speed  engines  should  remain  open  for 
a  considerable  period  after  the  crank  passes  the  outer  dead 
center  on  the  suction  stroke,  owing  to  the  inertia  of  the  gases 
which  tends  to  fill  the  cylinder.  Lengthening  the  period  of 
opening  of  the  inlet  valve  in  multiple  cylinder  engines  produces 


GAS,  OIL  AND  STEAM  ENGINES  319 

better  carbureting  conditions  and  reduces  the  variations  of  pres- 
sure in  the  manifold. 

EXHAUST  VALVES.  The  exhaust  valve  should  begin  to 
open  40°  BEFORE  the  crank  reaches  the  OUTER  dead  center 
on  the  working  stroke,  and  should  close  10°  AFTER  the  crank 
has  passed  the  inner  dead  center. 

INLET  VALVES.  The  inlet  valve  should  open  15°  AFTER 
the  crank  passes  the  inner  dead  center  on  the  suction  stroke, 
and  should  close  35°  after  the  crank  passes  the  outer  dead  center. 

The  inlet  valve  should  never  open  before  the  exhaust  valve 
closes,  although  this  is  done  on  several  types  of  high  speed 
aeronautical  engines.  The  makers  of  these  engines  claim  that 
this  practice  scavenges  the  combustion  chamber  more  thor- 
oughly and  makes  the  mixture  more  effective  owing  to  the  in- 
ertia of  the  burnt  gases  forming  a  partial  vacuum  in  the  com- 
bustion chamber.  The  writer  has  never  been  able  to  get  satis- 
factory results  with  this  timing  and  doubts  whether  it  can  be 
accomplished  successfully. 

In  timing  an  engine  great  care  should  be  taken  to  get  the 
crank  exactly  on  the  dead  center. 

(139)  Timing  Offset  Cylinders. 

The  only  difference  in  timing  engines  with  offset  cylinders 
and  timing  those  with  the  center  line  of  the  cylinder  in  direct 
line  with  the  crank  shaft,  is  in  the  locating  of  the  dead  center. 
With  no  offset,  the  center  of  the  cylinder,  the  crank  pin  and 
the  crank  shaft  are  all  in  one  direct  line  when  the  engine  is  on 
the  dead  center. 

With  offset  cylinders  the  crank  pin  lies  to  one  side  of  the  cyl- 
inder center  line  when  on  the  dead  center,  on  either  the  inner, 
or  the  outer  center.  To  find  the  center  on  an  offset  engine 
proceed  as  follows: 

Turn  the  engine  over  slowly  until  the  crank-pin  reaches  either 
the  extreme  top  or  bottom  point  of  the  crank  circle,  depending  on 
which  center  is  to  be  determined,  and  then  turn  very  slowly 
until  the  centers  of  the  piston-pin,  crank-pin,  and  crank-shaft 
are  in  line.  With  the  average  engine  this  will  be  found  a  dif- 
ficult and  tedious  job,  and  it  will  be  well  to  mark  the  dead  cen- 
ter on  the  flywheel  or  other  convenient  point  to  prevent  a  rep- 
etition of  the  job.  The  quickest  method  of  accomplishing  the 
feat  is  to  remove  the  spark  plug  or  relief  cock  to  gain  access 
to  the  piston,  and  insert  a  rod  or  pointer  in  the  opening  thus 
provided. 


320  GAS,  OIL  AND  STEAM  ENGINES 

Draw  the  piston  back  a  short  distance  from  the  end  of  the 
stroke  with  the  pointer  resting  on  the  head  of  the  piston,  and 
mark  this  position  of  the  piston  both  on  the  pointer,  and  on 
the  flywheel,  using  some  stationary  part  of  the  engine  as  a 
reference  point. 

Now  turn  the  crank  over  the  center  line  until  the  piston  is 
moving  in  the  opposite  direction,  and  is  the  same  distance  from 
the  end  of  the  stroke  as  shown  by  the  mark  on  the  pointer. 
Mark  this  position  on  the  flywheel  using  the  same  reference 
mark  as  before.  We  now  have  two  marks  on  the  flywheel,  and 
will  bisect  the  distance  between  them,  using  the  dividing  mark 
to  obtain  the  center. 

Place  the  bisection  mark  even  with  the  reference  point  used 
for  obtaining  the  two  previous  marks  on  the  flywheel,  and  the 
engine  will  be  on  the  true  dead  center,  as  the  flywheel  is  now 
midway  between  two  points  of  equal  stroke. 

(140)  Auxiliary  Exhaust  Ports. 

To  decrease  the  amount  of  hot  gas  and  flame  passing  over 
the  exhaust  valve  some  makers  provide  their  engines  with 
auxiliary  exhaust  ports,  which  are  similar  to  the  exhaust  ports 
used  on  two  stroke  cycle  engines. 

The  auxiliary  exhaust  consists  of  a  series  of  holes  drilled  or 
cored  through  a  rib  on  the  cylinder  wall,  the  holes  freing  so 
situated  that  they  are  covered  by  the  piston  until  it  is  at  the 
extreme  end  of  its  outward  stroke.  The  holes  are  not  un- 
covered until  the  burning  charge  has  been  expanded  and  cooled 
to  the  greatest  extent  possible  in  the  cylinder.  As  soon  as  the 
piston  uncovers  the  ports  the  greater  portion  of  the  dead  gas 
escapes  instantly  to  the  atmosphere,  carrying  with  them  the 
greater  percentage  of  the  heat  and  flame.  The  small  amount 
of  residual  gas  that  remains  is  forced  out  through  the  exhaust 
valve  in  the  usual  manner,  thus  no  flame  ever  reaches  the 
exhaust  valve. 

The  use  of  auxiliary  exhaust  ports  produces  a  cooler  cylinder 
as  the  gas  passes  over  the  cylinder  wall  only  once,  and  conse- 
quently is  in  contact  with  the  walls  only  one-half  of  the  time 
usual  with  the  ordinary  system.  The  cool  cylinder  lessens  the 
liability  of  PREIGNITION  and  decreases  the  consumption  of 
cooling  water  and  lubricating  oil.  Auxiliary  exhaust  ports  are 
particularly  desirable  on  air  cooled  engines. 


GAS,  OIL  AND  STEAM  ENGINES  321 

(141)  Valves  and  Compression  Leaks — Misfiring. 

Owing  to  the  intense*  heat  in  the  cylinder,  and  the  action  of 
the  gases  on  the  valves  the  seating  surfaces  become  ROUGH 
and  PITTED  which  causes  leakage  and  loss  of  compression. 
Exhaust  valves  cause  the  most  trouble  in  this  respect  as  they 
are  surrounded  by  the  hot  gases  during  the  exhaust  stroke 
and  are  much  hotter  than  the  inlet  valves. 

To  determine  the  value  of  the  compression,  turn  the  engine 
over  slowly  by  hand. 

Leaking  inlet  valves  usually  are  productive  of  BACK  FIR- 
ING or  EXPLOSIONS  IN  THE  CARBURETOR  intake  pas- 
sages, or  in  the  mixing  valves,  as  flame  from  the  cylinder 
leaks  through  the  valve  and  fires  the  fresh  gas  in  the  intake. 

MISFIRING  OR  LOUD  EXPLOSIONS  at  the  end  of  the 
EXHAUST  PIPE  are  indicative  of  leaky  exhaust  valves,  if  the 
mixture  is  correct  and  the  ignition  system  above  suspicion. 
Misfiring  caused  by  leaky  exhaust  valves  is  due  to  combustible 
mixture  escaping  from  the  cylinder  to  the  exhaust  pipe  and 
being  ignited  by  the  succeeding  exhaust  of  the  engine. 

If  the  engine  has  more  than  one  cylinder,  test  one  cylinder 
at  a  time,  opening  the  relief  valves  on  the  other  cylinders.  Now 
take  a  wrench  and  ROTATE  the  inlet  valve  on  its  seat,  for  it 
may  be  that  some  particles  of  carbon  or  dirt  have  been  deposited 
on  surface  of  the  valve  seat  which  prevents  the  valve  from 
closing  properly.  Rotating  the  valve  will  usually  dislodge  the 
deposit. 

Try  the  compression  again;  if  there  is  no  improvement,  rotate 
the  exhaust  valve  on  its  seat  in  the  same  manner,  and  repeat 
the  test  for  compression.  ROTATING  THE  VALVES  IN 
THIS  MANNER  WILL  OFTEN  MAKE  THE  REMOVAL 
OF  THE  VALVES  UNNECESSARY.  When  the  valves  are 
closed  the  end  of  the  valve  stem  should  NOT  be  in  contact  with 
the  PUSH  ROD,  or  cam  lever.  Suitable  CLEARANCE  should 
be  allowed  between  the  end  of  the  valve  stem  and  the  operat- 
ing mechanism  when  the  valve  is  closed;  this  clearance  varies 
from  the  thickness  of  a  visiting  card  on  small  engines  to  %  of 
an  inch  on  the  large.  If  the  valve  stem  is  continually  in  con- 
tact with  the  push  rod  it  cannot  seat  properly  and  consequently 
will  leak.  Wear  on  the  valve  seats  and  regrinding  reduces  this 
clearance,  wear  on  the  ends  of  valve  stems  and  push  rods  from 
continuous  thumping  increases  it.  Keep  the  clearance  constant 
and  equal  to  that  when  the  engine  was  new.  On  many  engines 


322  GAS,  OIL  AND  STEAM  ENGINES 

this  clearance  is  adjustable  to  allow  for  wear  by  lock  nuts  on 
the  ends  of  the  valve  stems  or  push  rods. 

If  the  above  attempts  have  proved  unsuccessful  remove  the 
exhaust  valve  from  the  cylinder,  if  the  valve  is  in  a  cage,  remove 
the  entire  cage;  this  may  easily  be  done  on  most  types  of  en-' 
gines.  Always  remove  the  exhaust  valve  first  as  the  inlet  valve 
rarely  requires  attention.  With  small  engines,  and  engines 
having  the  valves  mounted  directly  in  the  cylinder  head  it  will 
be  necessary  to  remove  the  cylinder  head  to  gain  access  to  the 
valves.  In  such  a  case  use  care  when  opening  the  packed  joint 
between  the  cylinder  and  head,  to  avoid  damaging  the  gasket. 

The  exhaust  valves  should  be  lubricated  with  Gas  Engine  Cyl- 
inder Oil,  never  with  common  machine  oil  on  account  of  gum- 
ming and  sticking,  or  with  gas  engine  cylinder  oil  thickened 
with  FLAKE  GRAPHITE.  Powdered  graphite  may  be  used 
with  success  without  the  addition  of  oil,  but  oil  makes  the 
application  of  the  graphite  much  easier. 

A  cracked  valve  seat,  due  to  expansion  strains  or  to  the 
hammering  of  the  valve,  is  a  common  cause  of  compression 
leakage,  and  is  rather  difficult  to  locate  as  the  leakage  only 
occurs  under  comparatively  high  pressure.  Leakage  may  also 
occur  between  the  valve  cage  and  the  cylinder  casting  unless 
pains  are  taken  to  thoroughly  clean  the  cage  and  the  bore  be- 
fore fastening  into  place. 

Warped  valves  are  caused  by  overheating,  the  head  of  pallet 
of  the  valve  becoming  out  of  square  with  the  stem,  or  by  twist- 
ing on  the  valve  seat.  If  warped  valves  are  suspected  the  high 
point  of  the  seat  may  be  determined  by  means  of  the  following 
test  and  should  be  carefully  filed  down  until  it  is  close  to  a 
bearing  after  which  it  may  be  ground  down  as  described  under 
pitted  valves. 

If  the  stems  are  now  in  good  condition  examine  the  seating 
surfaces  of  the  valve  pallets  and  cage  or  rings. 

The  seats  should  be  bright  and  free  from  pits,  depressions, 
or  streaky  blue  discolorations.  If  the  seats  are  deeply  grooved 
from  long  continued  leaks  it  is  best  to  discard  them  and  replace 
with  new. 

Pitted  valves,  and  those  slightly  grooved  or  streaked  should 
be  reground  by  the  use  of  a  little  emery  flour  and  tripoli  which 
operation  is  performed  as  follows: 

Lift  the  valve  from  its  seat  and  apply  lubricating  oil  to  the 
seating  surface,  then  sprinkle  a  little  flour  or  emery  on  the  oiled 


GAS,  OIL  AND  STEAM  ENGINES  323 

surface  and  drop  the  valve  back  on  the  seat.  Do  not  use  coarse 
emery  nor  too  much  of  the  abrasive,  a  pinch  is  enough  and 
will  grind  as  rapidly  as  a  pound.  Take  care  to  drop  the  emery 
only  where  required,  do  not  sprinkle  it  over  the  engine  or 
working  parts  as  it  will  cause  cutting  and  the  destruction  of  the 
bearings. 

Now  turn  the  valve  around  in 'one  direction  for  about  a  half 
dozen  turns  and  then  in  the  other  direction  for  the  same  length 
of  time,  alternately,  at  the  same  time  applying  a  moderate  pres- 
sure on  the  valve.  Small  valves  may  be  rotated  with  a  large 
screw  driver  entered  in  the  slot  found  on  the  valve  plate,  but 
the  handiest  method  is  with  a  carpenter's  brace  in  which  is  in- 
serted a  screw-driver  bit. 

Never  turn  the  valve  around  and  around  in  one  direction 
continuously  as  this  movement  is  liable  to  cause  grooving,  alter- 
nate the  direction  of  rotation  frequently  with  occasional  back 
and  forth  movements  made  in  a  semi-circle. 

Do  not  press  heavily  on  the  valve,  use  only  enough  pressure 
to  insure  contact  between  the  two  seating  surfaces. 

The  valve  should  be  lifted  occasionally  from  the  seat  to  pre- 
vent grooving,  and  to  redistribute  the  abrasive,  and  then  dropped 
back,  after  which  the  grinding  should  proceed  as  before.  Re- 
move the  valve  after  it  turns  without  friction,  wipe  it  clean, 
apply  fresh  oil  and  emery  and  grind  once  more.  When  the 
grinding  has  removed  all  pits  and  ridges,  and  presents  a  smooth 
even  surface,  the  grinding  is  complete.  To  test  for  accuracy 
of  grinding  place  a  little  Prussian  Blue  on  the  seat,  if  the  valve 
is  ground  to  a  perfect  surface  the  blue  will  show  uniformly 
spread  over  the  seat,  if  the  grinding  is  incomplete  bare  places 
showing  high  spots  will  be  seen.  It  is  a  good  plan  to  finish  the 
grinding  by  using  a  little  Tripoli  with  oil  after  the  emery  has 
removed  the  pits  and  high  spots,  as  Tripoli  is  finer  than  emery 
and  will  smooth  down  scratches  made  by  the  emery. 

After  the  grinding  has  been  performed  to  your  satisfaction, 
wash  the  valve,  valve  stem,  and  guides  thoroughly  with  gaso- 
line and  kerosene  to  remove  the  smaller  traces  of  emery,  to 
prevent  wear  and  cutting. 

When  the  valves  are  ground  in  place  on  the  engine  stuff  up  all 
openings  or  parts  of  the  cylinder  to  prevent  the  emery  from 
gaining  access  to  the  bore.  After  grinding  is  complete  wipe 
off  surfaces  thoroughly  and  remove  waste  used  for  stuffing. 


CHAPTER  XHI 
GAS  ENGINE  GLOSSARY 

Report  of  the  Nomenclature  Division  of  the  Data  Com- 
mittee of  the  National  Gas  Engine  Association 

Accelerator.  A  type  of  throttle  control.  Usually  a  foot 
throttle  on  an  automobile. 

Accessory.  A  subsidiary  part  of  an  engine,  such  as  the  parts 
required  for  ignition,  carburetion,  lubrication  and  starting. 

Advance.     Spark.     The  distance  usually  measured  in  degrees 
of  arc,  that  the  spark  occurs  in  advance  of  the  dead  center. 

Air-cooled  motor.     See  engine — air-cooled. 

Air  starter.  A  device  for  starting  an  engine  with  com- 
pressed air. 

Ammeter  (Ampere-meter).  An  instrument  for  measuring 
the  amount  of  electric  current  flowing  in  a  conductor. 

Assembly.  The  act  of  combining  the  various  parts  of  the 
machine  into  a  finished  whole. — A,  drawing.  The  general  draw- 
ing of  the  machine  as  a  whole. 

Assembler.  A  mechanic  who  has  charge  of  the  assembling 
of  a  machine. 

Automatic  valve  (Also  called  suction  valve).  An  inlet  valve 
held  to  its  seat  by  a  light  spring  and  opened  by  atmospheric 
pressure  due  to  the  suction  of  the  piston;  in  a  carbureter  a  valve 
opened  by  the  vacuum  in  the  carbureter. 

Auxiliary  port.  In  a  four-cycle  engine,  an  exhaust  port, 
uncovered  by  the  piston  at  the  end  of  the  stroke;  in  a  two- 
cycle  engine,  an  intake  port  leading  to  the  crankcase. 

Axis.  A  line  passing  through  the  center  as  the  center  line 
of  a  crankshaft  or  the  center  line  of  a  cylinder. 

Back  fire.  An  explosion  in  the  intake  passages  of  an  engine. 
See  base  explosion. 

Baffle,  baffle  plate.  An  obstruction  in  the  path  of  a  fluid  for 
the  purpose  of  either  changing  its  direction  or  retarding  its 
velocity.  See  deflecting  plate. 

324 


GLOSSARY  325 

Balance,  running.  Any  part  of  a  machine  is  in  running  bal- 
ance when  the  arrangement  of  particles  in  the  rotating  part  is 
such  that  there  is  no  tendency  for  it  to  be  deflected  from  its 
prescribed  path  by  unbalanced  centrifugal  forces. — static  b.  A 
part  such  as  a  flywheel  is  in  a  static  balance  when,  being  free 
to  roll,  it  will  remain  in  any  position  on  a  level  surface. — b 
weight.  A  weight  either  a  part  of  or  attached  to  the  crankshaft 
to  counter-balance  the  effect  of  the  reciprocating  parts  and  the 
crank  pin  and  the  crank  arms. — b,  wheel.  Frequently,  but  erro- 
neously, used  for  flywheel. 

Base.  That  part  of  an  engine  containing  the  crankshaft. 
A  term  usually  employed  for  engines  in  which  the  crankshaft  is 
enclosed.  Compare  frame. 

Base  explosion.  An  explosion  in  the  crankcase  or  base. 
Usually  employed  in  reference  to  a  two-cycle  engine. 

Battery,  electric.  A  combination  of  two  or  more  electric 
cells. 

Bed,  engine.    See  frame. 

Benzene.  A  liquid  hydro-carbon,  with  a  formula  (C6H6). 
Formerly  derived  exclusively  from  coal  tar,  but  now  obtainable 
from  petroleum.  Compare  benzine. — b,  group.  Hydrocarbons 
of  the  formula  (C2H2n6). 

Benzine.  A  distillate  of  petroleum  between  gasoline  and 
the  petroleum  ethers. 

Benzol.  Crude  benzene.  Chiefly  a  mixture  of  benzene  and 
its  homologues. 

Benzoline.     Benzene. 

Blast  furnace  gas.     See  Gas. 

Bore,  of  cylinders.     Inside  diameter. 

Boss.     A  projection,  usually  cylindrical,  of  a  machine  part. 

Box.  See  bearing.  Strictly  speaking,  box  is  the  frame  con- 
taining the  anti-friction  part  of  a  bearing.  Sometimes  called 
bearing  shell. — b,  coil.  A  spark  coil,  usually  of  the  high  tension 
type,  enclosed  in  a  wooden  box. — b,  piston.  A  hollow  piston 
closed  at  both  ends. 

Brake  horsepower.  The  horsepower  delivered  by  an  en- 
gine or  motor  at  the  point  of  power  delivery.  So-called  because 
the  power  is  usually  determined  in  a  test  by  means  of  a  prony 
brake  or  other  form  of  absorption  dynamometer.  "Delivered" 
horsepower  is  preferred. 

Brass,  or  brasses,  bearing.  The  bronze  shells  of  a  bear- 
ing which  are  in  contact  with  the  rotating  shaft.  They  may  or 
may  not  be  faced  with  babbitt. 


326  GLOSSARY 

Breech.     The  closed  end  of  a  piston   or  a  cylinder. 

Built-up  flywheel.  A  flywheel  comprised  of  two  or  more 
pieces. 

Bulb,  hot.  In  certain  forms  of  oil  engine  an  unwater-jacketed 
cup  or  pocket  employed  for  the  purpose  of  ignition. 

Butterfly  throttle.  A  thin  disk  similar  to  the  damper  in 
a  stove  pipe  rotated  on  a  spindle  passing  at  right  angles 
through  the  axis  of  the  inlet  pipe. 

By-pass.     See   transfer  port. 

Cable,  ignition.  An  insulated  electric  conductor,  or  a  com- 
bination of  several  insulated  conductors. 

Cam.  A  rotating  part  of  a  machine  having  a  projection 
designed  to  give  variable  motion  to  another  part  bearing 
against  it. 

Camshaft.     A   shaft   carrying  one   or  more   cams. 

Cap  bolt,  cap  screw.  A  bolt  used  without  a  nut  to  screw  into 
one  of  the  parts  which  it  is  used  to  hold  together. 

Cap  stone.  A  flat  stone  sometimes  employed  for  the  top 
of  a  foundation.  • 

Carbureter.  A  device  by  means  of  which  the  air  entering  a 
liquid  fuel  engine  is  caused  to  pick  up  and  atomize  a  small 
quantity  of  the  liquid  fuel. 

Cell,  electric.  An  electric  couple  comprised  of  two  dis- 
similar metals  or  a  metal  and  a  metalloid  surrounded  by  a 
salt  of  an  acid  solution  which  will  produce  a  difference  of 
potential  between  the  solid  elements.  The  liquid  is  known  as 
the  electrolyte. — dry  c,  An  electric  cell  in  which  the  electro- 
lyte is  contained  in  some  absorbent  material. — storage  c, 
An  electric  cell  in  which  electrical  energy  is  transformed  into 
chemical  energy  and  stored  until  some  future  time  when  it  may 
again  be  obtained  in  the  form  of  electrical  energy. 

Charge.  In  a  gas  engine,  that  quantity  of  mixture  taken 
into  a  cylinder  at  one  suction  stroke. 

Clerk-cycle.  A  form  of  two  stroke  cycle  invented  by  Dugald 
Clerk  and  having  a  separate  charging  cylinder. 

Clutch.  An  engaging  device  for  connecting  a  driven  machine 
with  the  driver. 

Cock,  drain.  An  ordinary  pet  cock  used  for  letting  surplus 
oil  out  of  the  base  or  water  out  of  the  water  jacket. — relief  c, 
A  valve  or  pet  cock  connected  to  the  cylinder,  usually  to  the 
compression  space,  to  relieve  the  compression. — priming  c,  or 
cup.  A  small  pet  cock  of  special  form  with  the  cup  on  the  outer 
end  which  is  screwed  into  the  cylinder  and  is  employed  for  the 


GLOSSARY  327 

purpose  of  admitting  a  small  quantity  of  gasoline  to  the  cylinder 
for  starting. 

Co-efficient  of  unsteadiness.  The  allowable  variation  of  the 
speed  from  the  normal  speed  of  the  engine,  used  in  flywheel 
design. 

Coil.     See  spark  coil  and  jump  spark  coil. 

Compensating  valve.  In  a  carbureter,  a  valve  whose  function 
is  to  retain  the  proper  proportions  of  the  mixture  at  all  speeds. 

Compression,  compression  pressure.  The  pressure  in  pounds 
gage  secured  by  the  inward  movement  of  the  piston. — c,  space. 
.The  space  in  the  cylinder  back  of  the  piston  when  the  piston 
is  at  the  end  of  its  inward  stroke. — c,  stroke.  The  second  stroke 
of  the  four-stroke  cycle  in  which  the  charge,  already  drawn  in 
is  compressed  before  ignition. 

Connecting  rod.  A  mechanical  link  connecting  the  piston  to 
the  crankshaft. 

Consumption,  fuel.     See  fuel  consumption. 

Contact  points.  In  a  make-and-break  igniter  the  two  small 
pieces  of  metal  at  the  point  of  contact  between  the  insulated 
and  the  grounded  electrode,  and  between  which  the  spark  is 
made.  Frequently  made  of  a  nickel  alloy. 

Cooling  tank.  A  tank  of  comparatively  large  capacity  con- 
nected to  the  water  jacket  of  an  engine. 

Counter  balance.     See  balance  weight. 

Counter  bore.  An  enlargement  of  the  diameter  of  the  cyl- 
inder in  the  compression  space. 

Counter  weight.     See  balance  weight. 

Crank  case  or  chamber.  See  base,  c,  arm,  That  part  of 
the  crank-shaft  connecting  the  crank  pin  to  the  main  shaft, 
c,  pin.  That  part  of  the  crankshaft  to  which  the  outer  end  of 
the  connecting  rod  is  attached.  Sometimes  but  erroneously 
called  wrist  pin. — c,  pit,  Practically  synonymous  with  crank 
case,  but  usually  referred  to  the  lower  part  of  the  base. — c, 
shaft,  An  axle  or  shaft  carrying  a  cylindrical  portion  offset  from 
the  main  shaft  and  connected  thereto  by  means  of  arms  for 
transposing  the  reciprocating  motion  of  the  piston  into  rotating 
motion. — starting  c,  A  bent  lever  with  a  handle  for  turning  an 
engine  when  starting. — c,  web,  See  crank  arm. 

Crosshead.  A  guiding  member,  usually  employed  in  a 
double-acting  engine,  located  at  the  connection  of  the  piston  rod 
and  the  connecting  rod. 

Crude  oil.     Unrefined  oil  as  it  comes  from   the  well.     The 


328  GLOSSARY 

term  is  frequently,  but  erroneously,  applied  to  the  residuums  of 
the  refinery. 

Curve,  compression.  The  line  on  the  indicator  diagram  de- 
noting the  rise  of  pressure  during  the  compression  stroke. — 
expansion  c,  A  curve  on  the  indicator  diagram  showing  the  drop 
of  pressure  during  the  expansion  stroke. 

Cup,  grease.  A  device  for  supplying  lubricating  grease  to 
a  bearing — oil,  c.  A  device  for  supplying  oil  to  a  bearing  or 
similar  surface. — priming  c,  See  priming  cock. 

Cut-off  (Valve  closure).  A  term  usually  applied  in  a  steam 
engine  to  the  closing  point  of  the  admission  valve.  Sometimes 
used  in  the  internal  combustion  engine  to  indicate  the  time  of 
closure  of  the  inlet  valve. 

Cycle.  The  complete  series  of  operations  required  for  the 
functioning  of  a  heat  engine. — four  c,  Properly  four-stroke  cycle. 
A  cycle  requiring  four  strokes  or  two  revolutions  of  the  engine 
for  its  completion  as  follows:  Suction  stroke,  outward;  com- 
pression, stroke  inward;  expansion  stroke,  outward;  exhaust 
stroke  inward. — six  c,  Properly  six-stroke  cycle.  A  cycle  re- 
quiring six  strokes  of  the  engine  for  its  completion.  The 
strokes  are  as  follows:  Suction,  compression,  explosion,  ex- 
haust, suction  of  a  charge  of  air,  or  scavenging  charge,  and  ex- 
pulsion of  scavenging  charge.— two  c,  Properly  two-stroke  cycle. 
A  cycle  requiring  two  strokes  of  the  piston  for  its  completion. 
The  suction  stroke  and  the  exhaust  stroke  of  the  four-cycle  are 
eliminated,  the  outward  stroke  is  always  the  expansion  stroke. 
About  1/5  of  the  expansion  stroke  is  used  for  exhaust  and  ap- 
proximately 1/10  of  the  same  stroke  for  receipt  of  a  fresh  charge 
from  a  special  source  of  supply,  as  the  crank  case  or  a  charging 
pump  outside  of  the  cylinder.  The  inward  stroke  is  always  the 
compression  stroke. 

Cylinder.  The  hollow  cylindrical  portion  of  an  engine  in 
which  the  functions  of  the  cycle  take  place. — c,  head.  The 
closed  end  of  the  cylinder. — c,  jacket.  An  annular  space  about 
the  cylinder  containing  the  cooling  medium. — c,  bore.  The 
inner  diameter  of  the  cylinder. — c,  studs.  Studs  for  holding  the 
cylinder  to  the  base  or  frame. — c,  bolts.  Bolts  to  hold  the  cylin- 
der to  the  base  or  frame. 

Dead  center.  The  extreme  end  of  the  stroke  both  inward 
and  outward.  So-called  because  the  piston  comes  to  a  "dead" 
stop  for  a  small  fraction  of  time  before  it  starts  in  the  opposite 
direction. 

Deflecting  plate,  deflector.     In  a  two-cycle  engine  a  projec- 


GLOSSARY  329 

tion  on  the  piston  to  direct  the  incoming  charge  towards  the 
cylinder  head. 

Delivered  horsepower.  The  horsepower  delivered  to  the 
driving  shaft  or  to  the  belt  or  other  driving  means  exterior  to 
the  engine  itself. 

Diagram,  indicator.  The  trace  drawn  by  the  pencil  or  stylus 
of  the  indicator. 

Diameter  of  cylinder.     See  bore. 

Die-cast  bearing.     Bearing  cast  in  metal  dies. 

Diesel  cycle.  A  high  pressure  cycle  of  either  the  two-cycle 
or  the  four-cycle  type  in  which  pure  air  only  is  compressed, 
and  the  fuel  is  injected,  usually  by  air-,  at  or  near  the  end  of  the 
compression  stroke.  The  term  is  usually  applied  to  engines  de- 
pending entirely  upon  the  heat  of  the  compression  to  ignite  the 
fuel  without  the  aid  of  any  other  ignition  means. 

Differential  piston.  A  piston  having  two  or  more  portions 
of  different  diameters. 

Discharge,  water.     Water  outlet. 

Distillate.  A  liquid  petroleum  derivative  with  a  specific 
gravity  between  gasoline  and  kerosene  The  term  is  usually 
applied  to  a  product  of  Pacific  coast  petroleum. 

Distributor.  Virtually  a  commutator  for  the  high  tension 
spark  in  jump  spark  ignition.  Usually  made  to  operate  syn- 
chronously with  the  circuit  breaker. 

Double-acting.  Applied  to  either  an  engine  or  a  pump  in 
which  functions  of  the  cycle  are  performed  on  both  sides  of 
the  piston. 

Drop,  in  two-cycle  ports.  The  distance  measured  along  the 
axis  of  the  cylinder  between  the  opening  of  the  exhaust  and  the 
opening  of  the  inlet  from  the  transfer  port. 

Dual,  ignition.  An  arrangement  whereby  a  magneto  may  be 
used  for  battery  ignition,  usually  temporarily  for  starting. 

Duplex  engine.  Occasionally  applied  to  a  two-cylinder  en- 
gine with  the  cylinders  parallel. 

Duplex  ignition.  A  system  of  ignition  whereby  two  spark 
plugs  may  be  used  simultaneously. 

Dynamometer.  A  device  for  measuring  the  horsepower  of 
an  engine  or  motor. — absorption  d,  A  dynamometer  in  which 
the  power  is  absorbed  in  the  dynamometer  itself. — transmission 
d,  One  in  which  the  power  is  measured  during  its  transmission 
to  power  driven  apparatus. 

Economy,  fuel.  The  amount  of  fuel  required  per  horse- 
power hour.  See  fuel  consumption. 


330  GLOSSARY 

Effective  port  area.  That  area  which  gives  the  required 
speed  of  the  gases  as  computed  on  the  assumption  that  the 
valve  or  port  is  fully  open  when  open  at  all. 

Efficiency.  The  ratio  between  actual  performance  and  theo- 
retical perfection. — thermal  e,  The  ratio  of  the  delivered  to 
the  indicated  horsepower. — thermal  e,  The  ratio  between  the 
amount  of  heat  transformed  into  work  and  the  heat  value  of 
the  fuel  required  to  perform  that  work. — volumetric  e,  The  ratio 
of  the  actual  volume  of  the  charge,  measured  at  atmospheric 
pressure,  to  the  piston  displacement  of  the  engine. 

Electric  ignition.  Any  form  of  ignition  depending  upon  elec- 
tric current  for  its  functioning. 

Electrode,  of  the  spark  plug.  The  terminal  wire  of  the  plug 
inside  the  cylinder  through  which  the  spark  passes.  Generally 
the  terminals  of  conductors  performing  any  function. — movable 
e,  In  a  make-and-break  igniter  the  rocking  contact  arm. — sta- 
tionary'e,  In  a  make-and-break*  igniter  the  insulated  contact  rod. 

Electric  dynamometer.  A  form  of  dynamometer  of  which 
an  electric  generator  forms  the  principal  part. 

Electric  starter.  An  electric  motor  for  turning  an  internal 
combustion  engine  to  start  it. 

Entropy.  A  function  of  heat  change.  It  is  the  quotient  of 
the  heat  change  divided  by  the  absolute  temperature  at  the 
instant  of  change. 

Engine,  air-cooled.  An  engine  with  cylinders  cooled  by  di- 
rect contact  with  air. — Diesel  e,  Any  engine  using  the  Diesel 
cycle  (which  see). — gas  e,  An  internal  combustion  engine  using 
gas  for  fuel. — oil  e,  An  internal  combustion  engine  using  oil  for 
fuel. — hot  bulb  e,  An  internal  combustion  engine  using  a  hot 
bulb  or  unjacketed  pocket  for  ignition. — internal  combustion  e, 
An  engine  wherein  the  fuel  is  entirely  consumed  inside  the 
working  cylinder. — two-cycle  e,  See  cycle. — four-cycle  e,  See 
cycle. — portable  e,  An  engine  mounted  on  a  wheel  truck. — 
semi-Diesel  e,  A  popular  term  for  a  hot  bulb  engine. — six-cycle 
e,  See  cycle. 

Exhaust  n.  Gases  discharged  from  the  cylinder,  usually  the 
products  of  combustion. 

Exhaust,  water.  Water  discharged  from  the  water  jacket. — 
e,  manifold.  That  part  of  the  exhaust  passages  immediately 
connected  to  the  cylinder. — e,  pipe.  A  pipe  connected  to  the 
exhaust  manifold  or  to  the  muffler  for  carrying  the  exhaust 
gases  to  the  point  of  discharge  into  the  atmosphere. — e,  port. 
An  opening  in  the  cylinder  wall  for  the  discharge  of  the  exhaust 


GLOSSARY  331 

gases. — e,  stroke.  The  fourth  stroke  of  a  four-stroke  cycle, 
during  which  the  exhaust  gases  are  discharged  from  the  cylinder. 
— e,  timing.  Points  measured  in  circular  degrees  at  which  the 
exhaust  valve  or  exhaust  port  opens  and  closes. — e,  valve.  The 
valve  closing  the  opening  into  the  cylinder  through  which  the 
exhaust  is  discharged. 

Exhaust  (verb).  The  act  of  discharging  material,  such  as 
waste  gases  from  the  cylinder  or  water  from  the  water  jacket. 

Expansion.  Increase  in  volume. — e,  curve.  The  line  on  the 
indicator  diagram  indicating  the  pressures  in  the  cylinder  in  re- 
lation to  the  various  points  in  the  stroke. — e,  stroke.  The  third 
stroke  of  a  four-stroke  cycle  during  which  the  gases  expand 
and  perform  work  upon  the  piston. 

Explosion.  A  sudden  increase  in  pressure  or  volume  usually 
caused  by  combustion. — e,  line.  The  line  of  the  indicator  dia- 
gram showing  the  increase  in  pressure  after  ignition. — premature 
e,  An  explosion  caused  by  too  early  ignition  during  the  com- 
pression stroke. 

Explosive  mixture.  A  mixture  of  combustible  fuel  and  air 
in  such  proportions  that  explosion  will  result  on  ignition. 

Flame  ignition.  Ignition  by  exposure  of  the  charge  to  a 
naked  flame. — f,  propagation.  The  advance  of  combustion 
throughout  the  charge  following  ignition. 

Float.  A  part  of  the  carbureter  lighter  than  the  fuel  and 
employed  to  regulate  the  height  of  fuel  in  the  nozzle. — f, 
chamber.  That  part  of  the  carbureter  containing  the  float. 

Flooding.  Excess  of  liquid  fuel  in  the  intake  passages  or 
in  the  cylinder. 

Flywheel.  A  heavy  wheel  attached  to  the  crankshaft  of  the 
engine  to  prevent  excessive  fluctuation  in  speed. 

Foundation.  A  mass  of  concrete,  stone,  brick  or  other  ma- 
terial on  which  the  engine  is  mounted. 

Four-cycle.     See  cycle. 

Four-port  motor.  A  two-cycle  motor  using  crankcase  com- 
pression, provided  with  both  a  suction  valve  and  a  piston  con- 
trolled crankcase  port. 

Forward  stroke.     See  stroke,  outward. 

Frame.  That  part  of  the  engine  attached  to  the  foundation 
and  carrying  the  crankshaft  bearings,  etc. — sub  f,  In  engines 
of  large  size  the  frame  is  made  in  two  parts,  the  frame  proper, 
carrying  the  crankshaft  bearings,  and  the  sub  frame  being  un- 
derneath the  frame  proper  between  it  and  the  foundation. 

Fuel  consumption.    The  amount  of  fuel  required  per  horse- 


332  GLOSSARY 

power  hour  to  operate  an  engine,  usually  measured  in  pounds  for 
liquid  fuel  and  cubic  feet  for  gaseous  fuels. 

Gap,  spark.  In  jump-spark  ignition  the  distance  between  the 
points  of  the  spark  plug  or  between  any  two  separate  parts  of 
the  high  tension  circuit;  a  device  usually  mounted  exterior  to  the 
engine  containing  an  opening  in  the  high  tension  circuit. 

Gas.  Aeriform  elastic  fluid.  For  example,  air,  oxygen,  hy- 
drogen, etc.,  are  all  gases. — air  g,  Term  generally  used  for  air 
charged  with  gasoline  vapor. — artificial  g,  Any  manufactured 
gas,  usually  confined  to  gas  manufactured  by  the  distillation  of 
coal  for  domestic  use. — Blast  furnace  g,  Gas  made  in  the  blast 
furnace  during  the  reduction  of  iron  ore. — coal  g,  Gas  made  by 
the  distillation  of  coal. — illuminating  g,  Gas  manufactured  for 
illuminating  purposes. — oil  g,  Gas  made  from  oil. — producer  g, 
Gas  manufactured  by  the  incomplete  combustion  of  either  a 
solid  or  a  liquid  fuel,  principally  carbon  monoxide. — water  g,  Gas 
usually  manufactured  from  coal  by  the  partial  combustion  of 
the  fuel  combined  with  the  disassociation  of  water. 

Gas  engine.  An  internal  combustion  engine,  strictly,  one 
using  gas  as  fuel. 

Gasoline.  Usually  a  fuel  with  a  distillation  range  of  100° 
to  400°  F. 

Gasoline  engine.  An  internal  combustion  engine  using  gaso- 
line as  a  fuel. 

Gas  producer.  A  device  for  the  manufacture  of  producer 
gas. 

Gas  tractor.  A  farm  or  road  locomotive  powered  with  an 
internal  combustion  engine. 

Governor.  Any  device  for  regulating  the  speed  of  an  engine 
so  as  to  maintain  it  between  certain  limits. — centrifugal  g,  A 
governor  depending  uf>on  the  change  in  centrifugal  force  due  to 
change  of  speed. — electric  g,  A  governor  regulating  by  the 
change  in  voltage  of  a  generator. — Hit-or-miss  g,  A  method  of 
governing  by  omitting,  entirely,  one  or  more  explosions. — throt- 
tling g,  A  method  of  governing  by  choking  the  inlet  passages. — 
g,  valve  A  valve  for  controlling  the  amount  of  mixture  passing 
through  the  inlet  passages. 

Head,  cylinder.  See  cylinder  head. — h,  end.  The  end  of  an 
engine  opposite  that  carrying  the  crankshaft,  piston  h,  the  piston 
proper  in  a  double-acting  engine, — valve  in  h,  engine.  An  engine 
having  the  valve  in  the  cylinder  head. 

Heat,  analysis.  A  test  to  determine  the  distribution  of  heat 
in  the  operation  of  a  heat  engine. — h,  balance.  The  result  ob'- 


GLOSSARY  333 

tained  by  heat  analysis. — h,  of  combustion.  The  heat  given  off 
when  burning  a  unit  quantity  of  fuel.  The  unit  generally  being 
one  pound. — h,  engine.  Any  prime  mover  deriving  its  power 
from  the  expenditure  of  heat. — h,  unit.  A  measure  of  heat. 
English  unit,  the  amount  of  heat  required  to  raise  a  pound  of 
water  16°  Fahrenheit;  known  as  the  British  Thermal  Unit  or 
B.  T.  U.  Metric  unit,  the  amount  of  heat  required  to  raise  a 
grain  of  water  1°  centigrade;  known  as  a  calorie. — h,  value,  high. 
The  heat  of  combustion  of  a  fuel  including  the  latent  heat  of 
steam  for  the  hydrogen  content. — h,  value,  low.  The  heat  of 
combustion  less  the  latent  heat  of  steam  for  the  hydrogen 
content. 

High-tension  ignition.     See  ignition,  high  tension. 

Hit-or-miss  governor.     See  governor,  hit-or-miss. 

Hopper.  A  form  of  water  jacket  enlarged  or  extended  at 
the  top  to  form  a  reservoir. — ,  cooled.  An  engine  having  an 
open  jacket. 

Horizontal  engine.  One  in  which  the  axis  of  the  cylinder 
is  normally  parallel  to  the  earth's  surface. 

Horsepower,  (Note  this  word  should  be  written  without  a 
hyphen).  The  expenditure  of  3,300  foot  pounds  in  one  minute. — 
brake,  h.p.  The  power  derived  by  a  brake  test. — delivered  h.p., 
The  power  delivered  to  the  belt  or  other  means  of  transmission. 
— draw  bar  h.p.,  The  power  based  on  the  pull  at  the  drawbar 
of  a  locomotive  or  tractor. — electric  h.p.,  745.941  watts. — indi- 
cated h.p.,  The  horsepower  based  on  the  mean  effective  pressure 
as  shown  on  the  indicator  diagram. — metric  h.p.,  4,500  kilo- 
gram-meters per  minute. — h.p.,  nominal.  The  rated  or  catalog 
horsepower  of  an  engine. — h.p.,  of  water.  Indian  government 
standard,  15  cubic  feet  falling  1  ft.  in  one  second. 

Hot  bulb  engine.  An  engine  in  which  the  charge  is  ignited 
with  a  hot  bulb. 

Hot  bulb  ignition.     See  ignition,  hot  bulb. 

Hot  plate  ignition.     See  ignition,  hot  plate. 

Hot  tube  ignition.     See  ignition,  hot  tube. 

Housing.  A  term  of  varying  significance  frequently  em- 
ployed to  denote  the  frame  or  crankcase  of  an  engine. 

Hydrocarbon.  A  substance  formed  chiefly  of  hydrogen  and 
carbon  in  chemical  combination. 

Ignite.     To  set  fire  to. 

Igniter.     A  device  which  ignites. 

Ignition.  The  act  of  igniting. — battery  i,  Electrical  ignition 
having  as  its  primary  source  of  electrical  pressure,  an  electric 


334  GLOSSARY 

battery. — catalytic  i,  Contact  ignition,  said  of  ignition  pro- 
duced by  the  rise  of  temperature  caused  by  .  the  gas  or 
mixture  coming ,  in  contact  with  some  material  like  spongy 
platinum. — flame  i,  See  flame  ignition. — high  frequency  i,  Elec- 
tric ignition  by  means  of  a  high  frequency  alternating  current. 
Usually  that  form  of  current  produced  by  a  condenser  discharge. 
— high  tension  i,  Ignition  caused  by  a  current  of  sufficiently 
high  voltage  to  make  the  spark  leap  an  open  gap — jump  spark 
i. — hot  bulb  i,  Ignition  by  means  of  an  unwater-cooled  pocket  in 
the  engine  cylinder. — hot  plate  i,  Ignition  by  means  of  an 
unwater-cooled  plate  attached  either  to  the  inside  of  the  cylinder 
hear  or  to  the  end  of  the  piston  and  heated  by  the  combustion 
of  the  cylinder. — hot  tube  i,  Ignition  by  means  of  a  tube 
heated  by  a  flame  exterior  to  the  tube. — jump  spark  i,  See 
high  tension  ignition. — magneto  i,  Electrical  ignition  hav- 
ing as  its  primary  source  of  electrical  pressure,  a  magneto. — 
premature  i,  Ignition  taking  place  before  the  proper  time  in  the 
cycle. — -i,  system.  The  method  and  apparatus  used  in  any 
form  of  ignition. 

Illuminating  Gas.     See  gas,  illuminating. 

Indicated  horsepower.     See  horsepower,  indicated. 

Indicator.  An  instrument  for  registering  the  pressures  at 
different  points  in  the  cycle. — i,  card.  A  sheet  of  paper  on  which 
the  indicator  diagram  is  recorded. — i,  diagram.  The  trace  of 
the  indicator  pencil  or  stylus  on  the  indicator  card. — gas  engine 
i,  A  special  form  of  indicator,  usually  with  a  Y$  in.  area  piston 
for  indicating  a  gas  engine. 

Inertia  governor.  A  governor  utilizing  the  properties  of 
inertia  for  the  regulation  of  an  engine.  Usually  employed  in  a 
hit-or-miss  governor  only. 

Inflammation,  period  of.  The  time  elapsing  between  the 
instant  of  ignition,  and  the  instant  at  which  the  ^ntire  charge 
has  been  ignited. 

Inlet  manifold.  That  part  of  the  engine  containing  the 
passages  from  the  carbureter  to  the  cylinder. — i,  port.  The  open- 
ing in  the  cylinder  wall  through  which  the  charge  is  drawn  in. — 
i,  stroke.  The  first  stroke  in  a  four-stroke  cycle  during  which 
the  charge  is  drawn  into  the  cylinder. — i,  valve.  The  valve  con- 
trolling the  opening  from  the  inlet  manifold  to  the  cylinder. 

Intake.     Synonymous  with  inlet. 

Internal  combustion  engine.  See  engine,  internal-combus- 
tion. 


GLOSSARY  335 

Inward  stroke.  The  stroke  during  which  the  piston  is  ap- 
proaching the  cylinder  head. 

Isothermal.     Without  change  of  temperature! 

Isopiestic.     Without  change  of  pressure. 

Jacket.  In  a  gas  engine,  a  hollow  space  surrounding  some 
portion  of  the  engine,  such  as  the  water  jacket  around  the  cyl- 
inder.— water  j.  A  jacket  containing  water,  as  the  water  jacket 
around  the  cylinder — heater  j.  A  jacket  surrounding  the  inlet 
passages  for  the  reception  of  either  hot  water  or  hot  exhaust 
gas,  or  a  jacket  connected  with  the  inlet  passages  and  surround- 
ing the  exhaust  pipe. — manifold  j.  A  jacket  surrounding  either 
the  intake  or  the  exhaust  manifold. 

Journal.     See  bearing. 

Junk  Ring.  A  ring,  usually  forming  a  part  of  the  piston, 
separating  the  piston  rings,  derived  from  the  ring  used  to  clamp 
the  hemp  or  similar  packing  (junk)  .used  in  the  early  steam 
engines. 

Jump-spark  ignition.     See  high-tension  ignition. 

Kerosene.  A  product  of  the  fractional  distillation  of  petro- 
leum having  a  gravity  of  40°  to  46°  Baume  and  with  other 
characteristics  usually  fixed  by  State  or  National  Law.  Lamp 
oil. 

Lag  of  magnet.  The  time  required  for  an  electro-magnet  to 
reach  its  full  strength  after  closing  the  circuit,  magnetic  inertia. 

Lag  of  spark.  The  time  elapsing  between  the  operation  of 
the  timing  device  and  the  production  of  the  spark. 

Lag  of  valve.  The  distance  measured  in  the  direction  of 
the  piston  travel  or  in  degrees  on  the  crank  circle  that  a  valve 
remains  open  after  the  piston  has  passed  the  dead  center. 

Latent  heat,  of  steam.  The  amount  of  heat  required  to  trans- 
form water  from  a  liquid  form  into  steam  at  boiling  temperature; 
of  melting  ice,  the  heat  required  to  transform  ice  into  water 
at  the  melting  temperature. 

Lay  shaft  (obsolete).    See  cam  shaft. 

Lead,  of  valves.  The  time  measured  along  the  travel  of  the 
piston  or  in  degrees  on  the  crank  circle  that  the  valve  opens 
in  advance  of  the  dead  center. 

Lean  mixture.  A  mixture  of  fuel  and  air  in  which  there  is 
much  more  air  than  required  for  complete  combustion. 

Lift  of  valves.  The  amount,  measured  in  the  direction  of 
travel,  that  a  valve  is  raised  from  its  seat. 

Locomotive,  gasoline.  A  locomotive  which  is  driven  by  a 
gasoline  engine  through  gearing. — gasoline-electric  1.  A  loco- 


336  GLOSSARY 

motive  driven  by  a  gasoline  engine  through  an  electrical  trans- 
mission. 

Load,  brake.  The  load  on  the  end  of  the  arm  of  a  prony 
brake.  Occasionally  used  to  denote  brake  horsepower. 

Low-tension  ignition.  Ignition  produced  by  breaking  a  cir- 
cuit of  low  voltage. 

Load,  rated.     See  horsepower,  nominal. 

Low-tension  magneto.  A  magneto  designed  for  low  ten- 
sion ignition  delivering  current  at  about  eight  volts. 

Lubricant.     Anything  which  lubricates. 

Lubricate.  To  reduce  friction  by  means  of  an  oil,  grease  or 
equal  material.  Otherwise  to  apply  a  lubricant. 

Lubrication.     The  act  of  lubricating. 

Magnetic  igniter.  A  low-tension  igniter  in  which  the  circuit 
is  broken  by  an  electro-magnet. 

Magneto.  An  electric  generator  having  permanent  mag- 
nets for  the  field. — high  tension,  low  tension,  dual,  duplex,  inde- 
pendent m.  See  ignition. 

Main  bearing.     See  bearing,  main. 

Make-and-break  igniter.  A  low-tension  igniter  in  which  the 
igniter  points  are  brought  together  and  separated  mechanically 
in  the  combustion  space,  (hammer-break  igniter.)  Sometimes 
used, instead  of  make-and-break  igniter.  The  term  is,  however, 
not  sufficiently  inclusive. 

Maker,  contact  In  an  ignition  apparatus  a  device  for  closing 
the  circuit  mechanically  at  the  moment  of  ignition. 

Manifold.     See  inlet  manifold,  exhaust  manifold. 

Manograph.  A  form  of  gas-engine  indicator  in  which  the 
diagram  is  produced  by  means  of  a  ray  of  light  reflected  from  a 
mirror  attached  to  a  diaphragm,  the  latter  being  acted  upon  by 
the  pressure  within  the  cylinder. 

Marine-type  connecting  rod.  A  type  of  connecting-rod  in 
which  the  bearings  are  held  in  place  by  a  bolted  cap. 

Marine  engine.  An  engine  designed  to  propel  a  boat  or  a 
ship. 

Master  vibrator.  In  a  group  of  jump-spark  coils  a  vibrator 
which  functions  each  of  the  coils  in  turn. 

Mean  effective  pressure  (M.E.P.).  The  average  net  pres- 
sure developed  during  a  cycle,  as  shown  by  the  indicator  dia- 
gram. 

Mechanical  efficiency  (M.E.).  The  ratio  of  the  brake  or  de- 
livered horsepower  to  the  indicated  horsepower. 


GLOSSARY  337 

Mixer.  A  term  frequently  employed  to  designate  a  simple 
form  of  carbureting  device  or  mixing  valve.  See  mixing  valve. 

Mixing  valve.  A  check  valve  form  of  carbureting  device 
in  which  the  lift  of  the  check  valve  opens  the  passage  into 
the  gasoline  supply. 

Mica  plug.  A  spark  plug  in  which  the  insulation  is  made  of 
mica. 

Misfire.     Failure  to  explode. 

Mixture.  The  combination  of  fuel  and  air  drawn  into  the 
cylinder  during  the  suction  stroke.  Compare  charge. 

Motor.  See  engine.  (Note — engine  is  rapidly  gaining  in  favor 
among  engineers  in  general.) 

Motor,  automobile.  An  engine  designed  to  drive  an  automo- 
bile.— Airplane  m,  An  engine  designed  to  drive  an  airplane. — 
Diesel  m.  See  engine  Diesel. — marine  m.  See  marine  engine. — 
semi-Diesel  m.  A  term  employed  for  the  hot  bulb  engine,  but 
now  gradually  increasing  in  disfavor. — super-Diesel  m.  A  term 
employed  by  some  manufacturers  to  designate  a  motor  employ- 
ing the  Brons  cycle. 

Motor  car.     An  automobile. 

Motor  Boat.  A  boat  driven  by  an  internal  combustion 
engine. 

Motor  fire  apparatus.  A  fire  engine  or  other  apparatus 
propelled  by  a  gasoline  engine. 

Muffler.     A  device  for  quieting  the  sound  of  the  exhaust. 

Multi-cylinder  (adjective).     Having  two  or  more  cylinders. 

Mushroom  valve.     A  poppet  valve. 

Naptha.  A  hydrocarbon  of  rather  uncertain  constitution. 
The  term  is  frequently  employed  as  a  synonym  to  gasoline. 
Scientifically  a  term  applied  to  the  lighter  shale  oils  with  a 
specific  gravity  of  about  .765. 

Napthalene.  A  solid  hydrocarbon  having  the  formula 
(C10H8). 

Napthene.  A  group  of  hydrocarbons  having  the  general 
formula  (CnH2n). 

Napthol.     An  alcohol  with  the  chemical  formula  (C10H7OH.) 

Natural  gas.     Gas  obtained  from  underground. 

Needle  valve.  A  sharply  pointed  valve  in  a  carbureter  whose 
function  is  to  regulate  the  admission  of  fuel  into  the  air  stream. 

Nozzle.  The  end  of  the  stand-pipe  in  a  carbureter  through 
which  the  liquid  fuel  is  admitted  to  the  air  stream. 

Oil  (as  a  fuel).  A  term  usually  applied  to  any  combustible 
liquid  having  a  dry  point  above  400°  F.  The  term  applies  not 


338  GLOSSARY 

only  to  petroleum  products  but  to  combustible  liquids  of  other 
derivation. 

Oil.  A  term  usually  applied  to  a  large  variety  of  liquids  of 
a  more  or  less  unctuous  nature  and  insoluble  in  water. 

Oil  groove.  A  groove  in  a  bearing  for  the  guidance  of 
lubricating  oil. 

Oil  Ring.  A  ring  resting  on  the  top  of  a  horizontal  shaft 
in  a  bearing  and  dipping  into  the  oil  in  an  oil  pocket.  The  rota- 
tion of  the  shaft  rotates  the  ring  by  friction  and  helps  it  to 
drag  the  oil  to  the  top  of  the  shaft. 

Oiler.    See  lubricator. 

Oil,  lubricating.     Any  oil  used  for  lubrication. 

Oil  engine  or  motor.  An  internal  combustion  engine  em- 
ploying any  of  the  fuel  oils. 

Otto  cycle.  The  usual  four  stroke  cycle.  Generally  con- 
sidered to  have  been  originated  by  Beau  de  Rochas,  but  ac- 
tually put  into  operation  by  Doctor  N.  A.  Otto  in  1876. 

Outlet     See  exhaust. 

Outlet  manifold.     See  exhaust  manifold. 

Packing  ring.     See  ring  piston. 

Paraffin  oil.     An  English  term  for  kerosene. 

Paraffin  wax.  One  of  the  lower  hydrocarbons,  usually  of  the 
Methane  group  and  solid  at  ordinary  temperatures.  It  is  usu- 
ally white  or  bluish  white,  and  devoid  of  either  taste  or  smell. 
It  contains  various  hydrocarbons,  and  it  has  about  15  per  cent 
of  hydrogen  and  85  per  cent  carbon. 

Passage,  inlet  An  opening  leading  from  the  carbureter  to 
the  inlet  valve. — exhaust  p.  The  passage  leading  from  the  ex- 
haust valve  to  the  exhaust  pipe  and  usually  considered  as  the 
exhaust  passage  in  the  exhaust  manifold. 

Pendulum  governor.  A  form  of  governor  employed  on  a 
hit-or-miss  engine,  depending  for  its  regulation  upon  the  inertia 
of  a  pendulum. 

Period  of  inflammation.     See  inflammation,  period  of. 

Petroleum.  A  natural  oily  liquid  obtained  from  underground, 
mineral  oil. 

Pin.     See  crank  pin,  piston  pin. 

Pipe,  exhaust.  Pipe  for  carrying  off  the  exhaust  gases. — 
inlet  p.  Usually  the  inlet  manifold  or  a  pipe  connected  to  the 
inlet  manifold. — water  p.  A  pipe  for  carrying  water  to  or  from 
the  water  jacket  of  an  engine. 

Piston.  A  sliding  cylindrical  part  fitting  into  the  cylinder 
of  an  engine  and  through  which  power  is  transferred  through 


GLOSSARY  339 

the  connecting  rod  to  the  crankshaft. — differential  p.  See  dif- 
ferential piston. — p,  head.  See  head,  piston. — p,  valve.  A  valve 
in  piston  form  regulating  the  intake  or  the  exhaust  or  both  by 
covering  and  uncovering  ports  in  the  walls  of  a  cylindrical 
valve  chamber. — p,  pin.  A  cylindrical  journal  for  connecting  the 
piston  to  the  end  of  the  connecting  rod. — trunk  p.  A  piston 
closed  at  one  end  only. — p,  rod.  A  cylindrical  rod  for  connect- 
ing the  piston  to  the  crosshead. — p,  speed.  Twice  the  stroke 
in  feet  multiplied  by  the  r.p.m. 

Pit,  exhaust.  A  form  of  large  muffler  hollowed  out  of  the 
ground. 

Plate,  handhole.    A  plate  or  cover  for  closing  a  handhole. 

Plug,  spark.     See  spark  plug. 

Plunger,  pump.  -  The  pump  piston. 

Poppet  valve.  A  disk  or  head  attached  to  a  cylindrical  stem 
of  comparatively  small  diameter  for  closing  an  opening  by  forc- 
ing it  tight  against  a  seat  adapted  to  fit  the  disk-shaped  head. 

Port.  An  opening  for  the  admission  or  the  discharge  of 
fluid. — p,  area.  The  area  of  a  cross  section  of  a  port. — exhaust 
p.  See  exhaust  port. — inlet  p.  See  inlet  port. 

Power.     See  horsepower. 

Pre-ignition.     See  ignition,  premature. 

Premature  explosion.  Explosion  caused  by  premature  igni- 
tion. 

Primary  coil.  An  induction  coil  with  a  single  winding, 
usually  employed  in  primary  or  low-tension  ignition. 

Primer.  A  device  for  inserting  a  combustible,  as  gasoline, 
into  a  cylinder. 

Priming  cup.     See  primer. 

Projected  area,  of  bearings.  The  length  of  the  bearing  multi- 
plied by  the  diameter. 

Puppet  valve.     See  poppet  valve. 

Push  rod.  In  a  valve  mechanism,  a  block,  usually  of  cylin- 
drical form,  intermediate  between  the  cam  and  the  valve  or  the 
valve  operating  mechanism. 

Push  rod,  roller  type.  A  push  rod  containing  a  roller  bearing 
against  the  cam. 

Push  rod,  mushroom  type.  A  push  rod  having  an  enlarged 
end  bearing  against  the  cam. 

Radiator.  As  applied  to  an  engine,  a  device  of  cellular  or 
tubular  structure  for  cooling  the  jacket  water. 

Range,  spark.  The  angular  distance  from  full  retard  to  full 
advance  in  a  timer. 

Rated  horsepower.    See  horsepower,  nominal, 


340  GLOSSARY 

Reciprocating  parts.  Parts  such  as  the  piston,  piston  rod, 
crosshead  and  connecting  rod,  that  move  back  and  forth,  usually 
in  the  direction  of  the  axis  of  the  cylinder. 

Reverse  gear.  A  device,  usually  applied  to  marine  engines, 
by  means  of  which  the  propeller  shaft  is  caused  to  run  in  the 
direction  opposite  to  that  of  the  engine  crankshaft. 

Reversible  engine.  An  engine  which  may  be  reversed  in  di- 
rection independently  of  a  reverse  gear. 

Ring,  piston.  A  ring  of  metal,  usually  cast  iron,  cut  through 
in  one  or  more  places  and  so  constructed  that  its  periphery  is 
forced  into  contact  with  the  cylinder  walls. 

Rod,  connecting.     See  connecting  rod. 

Rod,  piston.     See  piston  rod. 

Roller  push  rod.     See  push  rod,  roller  type. 

Scavenging.  The  act  of  clearing  the  cylinder  of  the  residual 
burned  gas  or  that  gas  remaining  after  the  completion  of  the 
ordinary  exhaust  stroke.  Scavenging  is  secured  either  by  driv- 
ing air  through  the  combustion  space  or  by  mechanical  means, 
such  as  a  special  piston. 

Shaft,   crank.     See   crankshaft. 

Single  acting  engine.  An  engine  in  which  the  impulse  is 
given  at  one  end  of  the  piston  only, 

Spark  plug.  A  device  for  providing  the  spark  gap  in  the 
cylinder  for  jump  spark  ignition. 

Speed,  piston.     See  piston   speed. 

Starter.  A  device  for  setting  the  engine  in  motion  so  it  will 
take  up  its  cycle.  See  air,  electric  starter,  etc. 

Stationary  engine.    An  engine  for  driving  fixed  machinery. 

Stroke,  of  piston.  The  complete  movement  of  the  piston  in 
the  direction  of  the  axis  of  the  cylinder. — inward  s.  The  move- 
ment of  the  piston  toward  the  head  of  the  cylinder,  and  away 
from  the  crankshaft. — outward  s.  The  movement  of  the  piston 
toward  the  crankshaft. 

Suction  gas.  Producer  gas  secured  by  the  suction  of  the  en- 
gine drawing  air  through  a  bed  of  incandescent  fuel. 

Suction-gas  engine.  An  engine  operating  on  suction  gas. — 
s,  valve.  See  automatic  valve. 

Tandem  engine.  An  engine  having  two  pistons  on  the  same 
axis  and  connected  by  a  piston  rod. 

Thermal  efficiency.     See  efficiency,  thermal. 

Thermal  unit.     See  heat  unit. 

Thermal  unit,  Britsh.     See  heat  unit. 

Thermo-siphon  circulation.  Circulation  of  the  cooling  water 
caused  by  the  heat  in  the  water  jacket. 


GLOSSARY  341 

Three-port  motor.  A  form  of  two-cycle  motor  in  which  the 
passage  to  the  crankcase  is  through  a  piston-controlled  port. 

Throttle.  A  valve  for  choking  the  intake  passage  between 
the  carbureter  and  the  inlet  valve. 

Timer.  A  rotating  switch  for  closing  the  ignition  circuit  at 
the  proper  time  in  the  cycle. 

Two-cycle  engine.  An  engine  employing  the  two-stroke 
cycle. 

Tractor.     See  gas  tractor. 

Transfer  port.  The  passage  from  the  base  to  cylinder  of  a 
two-cycle  engine. 

Trunk,  piston.     See  piston,  trunk. 

Twin  engine.     Same  as  duplex  engine. 

Valve.  A  device  for  closing  an  opening  in  any  part  of  the 
engine.  See  definitions  under  various  heads,  as  automatic,  ex- 
haust, flat,  inlet,  etc. 

Vaporizer.  A  term  of  uncertain  significance  sometimes  ap- 
plied to  a  carbureter  and  sometimes  to  a  mixing  valve.  Seldom 
used. 

Vertical  engine.  One  in  which  the  axis  of  the  cylinder  is 
normally  vertical. 

Vibrator.  The  magnetic  circuit  breaker  of  a  jump  spark 
coil. 

Volumetric    efficiency.     See    efficiency,    volumetric. 

Water  carbureter.  A  simple  carbureter  for  supplying  water 
to  the  intake  of  a  kerosene  engine. — a,  gas.  See  gas,  water. — 
jacket  w.  See  jacket,  water. 

Wrist  pin.  The  piston  pin.  The  crank  pin  is  sometimes, 
but  erroneously,  termed  the  wrist  pin. 


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